LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


Class 


BY  THE   SAME  AUTHOR 


ELEMENTARY  ZOOLOGY 

Pp.  xv-f-492,  172  figs.,  i2mo,  1901, 

$1.20 
FIRST  LESSONS  IN  ZOOLOGY 

Pp.  x+363,  257  figs.,  i2mo,  1903, 

ll.ij 
AMERICAN  INSECTS 

Pp.  vii-f-67i,  812  figs.,   ii    colored 

plates,  8vo,  1905  (American  Nature 

Series,  Group  1),  $5.00.     Students' 

edition,  $4.00 

HENRY  HOLT  AND  COMPANY 

PUBLISHERS  NEW  YORK 


DARWINISM     TO-DAY 

A  DISCUSSION  OF  PRESENT-DAY  SCIENTIFIC  CRITICISM 
OF  THE  DARWINIAN  SELECTION   THEORIES,  TO- 
GETHER WITH  A  BRIEF  ACCOUNT  OF   THE 
PRINCIPAL  OTHER  PROPOSED  AUXIL- 
IARY AND  ALTERNATIVE  THEO- 
RIES OF  SPECIES-FORMING 


BY 


VERNON   L.    KELLOGG 

PROFESSOR    IN    LELAND    STANFORD,   JR.,    UNIVERSITY 


NEW   YORK 

HENRY  HOLT  AND  COMPANY 
1907 


COPYRIGHT,  1907, 

BY 
HENRY  HOLT  AND  COMPANY 

Published  August,  IQ&J 


THE   QUINN    4    BODEN    CO.    PRESS 
RAHWAY,    N.    J. 


PREFACE. 

THIS  book  is  written  for  the  sake  of  presenting  simply  and 
concisely  to  students  of  biology  and  to  general  readers  the 
present-day  standing  of  Darwinism  in  biological  science,  and 
to  outline  for  them  the  various  auxiliary  and  alternative 
theories  of  species-forming  which  have  been  proposed  to  aid 
or  to  replace  the  selection  theories. 

Our  actual  knowledge  of  the  factors  and  mechanism  of 
organic  evolution  and  our  hypotheses  and  theories  which 
serve  to  fill  in  the  present  gaps  in  this  knowledge  have  been 
greatly  added  to  and  modified  in  the  last  few  years.  Much 
that  the  general  reader  includes  in  his  conception  of  organic 
evolution,  based  on  his  reading  of  Darwin  and  Wallace  and 
Spencer,  has  been  materially  modified  and  some  of  it  proved 
untenable  by  modern  investigation;  while  much  which  had 
no  place  in  this  earlier  general  understanding  of  evolutionary 
method  and  process  may  now  be  confidently  added  to  it.  The 
present  time  is  one  of  unprecedented  activity  and  fertility 
both  in  the  discovery  of  facts  and  in  attempts  to  perceive 
their  significance  in  relation  to  the  great  problems  of  bio- 
nomics. Both  destructive  criticism  of  old,  and  synthesis  of 
new  hypotheses  and  theories,  are  being  so  energetically  car- 
ried forward  that  the  scientific  layman  and  educated  reader, 
if  he  stand  but  ever  so  little  outside  of  the  actual  working 
ranks  of  biology,  is  likely  to  lose  his  orientation  as  to  the 
trend  of  evolutionary  advance.  Precisely  at  the  present  mo- 
ment is  this  modification  of  the  general  point  of  view  and 
attitude  of  philosophical  biologists  unusually  important  and 
far-reaching  in  its  relation  to  certain  long-held  general  con- 
ceptions of  biology  and  evolution.  This  modification  of  the 
general  trend  of  evolutionary  thought  must  also  necessarily 

iii 


159201 


iv  PREFACE. 

strongly  affect  our  conceptions  of  the  underlying  principles 
of  such  correlated  sciences  as  sociology,  pedagogy,  etc.  It 
is,  then,  as  a  means  of  orientation  in  evolutionary  matters  for 
the  general  reader  and  for  the  unspecialised  but  interested 
student  of  science  that  this  book  is  prepared. 

That  it  may  not  be  without  some  special  usefulness  to 
more  advanced  students  and  biological  workers  there  are 
added,  in  appendices  to  the  chapters,  special  notes  (referred 
to  in  the  text  by  small  super-numbers)  in  which  are  given 
numerous  exact  references  to  general  or  special  books  or 
papers,  and  accounts,  in  more  or  less  detail,  of  particular 
observations,  experiments,  or  theoretical  discussions,  as  well 
as  references  to  extended  bibliographic  lists  of  the  subjects 
under  treatment.  These  notes  will  enable  students,  or  .others 
interested,  to  look  up  the  original  sources  of  our  knowledge 
of  the  subjects  of  the  various  chapters,  and  to  find  more 
detailed  general  or  special  discussions  of  them  than  can  be 
given  in  this  book.  These  notes  also  enable  the  author  to 
introduce  into  the  book  some  details  of  his  own  observations 
and  experiments  touching  various  evolutionary  subjects. 

V.  L.  K. 

STANFORD  UNIVERSITY,  June,  1907. 


CONTENTS. 

CHAPTER  /. 

PAGE 

INTRODUCTORY:      THE      "DEATH-BED      OF      DAR- 
WINISM"          i 

Modern  activity  in  biologic  study,  i.  Darwinism  not 
synonymous  with  evolution,  3.  Present-day  anti-Darwin- 
ism, 4.  Intemperate  anti-Darwinism,  6.  Outline  of  this 
book,  7. 

APPENDIX:  Dennert's  intemperate  attack  on  Darwinism, 
7.  An  anti-evolution  university  biologist,  8.  Friedmann's 
theory  to  replace  evolution  with  divergence,  8. 

CHAPTER   II. 

DARWINISM  AND  EVOLUTION  DEFINED  AND 

DISTINGUISHED  .  10 

Animal  and  plant  kinds  originate  in  one  of  three  ways, 
10.  The  theory  of  descent  defined,  n.  The  theory  of 
descent  given  validity  by  Darwin's  explanation  of  the 
cause  of  it,  12.  Darwinism  defined  and  analysed  into  its 
fundamental  assumptions  and  facts,  13.  Sources  of  scien- 
tific evidence  for  the  theory  of  descent,  17.  Relation  of 
theology,  philosophy,  pedagogy,  and  sociology  to  the 
theory  of  descent,  20. 

APPENDIX:  Accounts  of  history  of  the  descent  theory, 
22.  Books  giving  the  evidences  for  descent,  23.  Dis- 
cussions of  the  relation  of  descent  and  theology,  23. 
Discussions  of  the  relations  of  biology  and  philosophy,  24. 
Biology  and  sociology,  24. 

CHAPTER   III. 

DARWINISM   ATTACKED 25 

The  attack  of  the  theologians,  25.  The  present-day 
attack  of  the  scientific  men,  25.  Some  of  the  principal 
objections  to  natural  selection  summarised,  30.  Darwinian 
or  fluctuating  variations  too  small  to  serve  as  "handles" 


vi  CONTENTS. 

PAGE 

for  natural  selection,  36.  Many  specific  differences  are 
indifferent,  /".  e.,  not  adaptive,  38.  The  extinguishing  of 
the  extreme  variations  by  interbreeding,  44.  The  im- 
probability of  the  occurrence  of  the  right  variations  at  the 
right  time,  45.  The  difficulty  of  explaining  the  production 
by  natural  selection  of  specialisations  useful  only  in  highly 
complex  condition,  49.  The  objection  based  on  the  over- 
development of  specialisations,  53.  The  objection  based 
on  insufficient  time,  54.  The  objection  that  natural  selec- 
tion tends  to  preserve  the  type  rather  than  the  variants, 
and  hence  opposes  change,  56. 

APPENDIX:  Books  and  papers  on  variation,  57.  Cases  of 
marked  variation  in  parthenogenetic  animals,  58.  Varia- 
tion according  to  the  law  of  probabilities,  59.  Quetelet, 
the  discoverer  of  variation  according  to  the  laws  of  chance, 
61.  Example  of  trivial  variations,  62.  Nageli's  seven 
objections  to  species-forming  by  selection,  62.  Wolff's 
attack  on  the  selectionists'  assumption  of  the  appearance 
at  the  right  time  of  the  needed  variation,  64.  Example  of 
non-correlated  variability  in  bilaterally  repeated  organs, 
65.  Henslow's  antagonism  to  selection  as  an  explainer  of 
floral  correlations,  67.  Wolff's  objection  to  the  necessary 
assumption  of  identical  and  coincident  variation  in  re- 
peated structures,  as  feathers,  scales,  etc.,  67.  Example 
of  mal-adaption  in  the  egg-laying  habit  of  Phryganidia 
caltfornica,  68 — Pieper's  antagonism  to  the  selection  ex- 
planation of  colour  and  pattern  in  insects,  69. 


CHAPTER  IV. 

DARWINISM  ATTACKED   (Continued}          .        ...        .     70 

Objection  to  the  exclusively  linear  or  quantitative  char- 
acter of  the  fluctuating  or  Darwinian  variations,  70. 
Galton's  law  of  regression,  71.  Selection  may  produce 
evolution  (continuous  change)  but  not  species  (discontinu- 
ous series),  73.  Pfeffer's  objection  based  on  the  slowness 
of  species  transformation,  75.  The  difficulty  of  explaining 
the  sterility  of  species  by  selection,  76.  Selection  cannot 
explain  extreme  or  complete  degeneration  of  useless  parts, 
77.  Objections  to  the  assumed  rigour  of  the  struggle  for 
existence  and  to  the  actuality  of  intra-specific  or  personal 
selection,  79.  Indiscriminate  extermination  due  to  the 
fortune  of  position  and  time,  80.  The  necessity  of  sexual 


CONTENTS.  vu 

PAGE. 

selection,  a  discredited  theory,  for  the  support  of  the 
natural  selection  theory,  85.  Natural  selection  rests  on  an 
unwarranted  assumption  of  its  homology  with  artificial 
selection,  86.  Many  biologists  find  natural  selection 
unable  to  account  for  known  biologic  conditions,  89.  Sig- 
nificance of  the  concessions  of  Darwinians,  90.  Kor- 
schinsky's  extreme  anti-Darwinian  doctrine,  91.  Delage's 
"true  role  of  selection, "93.  Morgan's  rejection  of  natural 
selection  as  a  species-forming  factor,  93. 

APPENDIX:  Gal  ton's  statement  of  the  law  of  regression, 
97.  Wolff's  criticism  of  panmixia,  98.  Example  of  inef- 
fective panmixia,  100.  Example  of  progressive  degenera- 
tion inexplicable  by  natural  selection,  100.  Wolff's 
discussion  of  the  selection  coefficient,  101.  Example  of 
non-selection  of  trivial  differences,  103.  References  to 
books  and  papers  on  plant  breeding,  105. 


CHAPTER    V. 

DARWINISM   ATTACKED  (Continued)-.    THE  THEORY 

OF  SEXUAL  SELECTION        .        .        ....        .106 

Secondary  sexual  differences  or  characters,  107.  Classi- 
fication of  secondary  sexual  characters,  107.  Useless  and 
harmful  characters  not  explicable  by  natural  selection, 
no.  Theory  of  sexual  selection  to  account  for  them:  the 
theory  defined,  in.  Darwin's  assumptions  as  basis  of  the 
theory  of  sexual  selection,  112.  Difficulties  in  the  way  of  a 
general  application  of  the  theory,  113.  The  theory  appli- 
cable only  to  species  in  which  males  are  more  numerous 
than  females,  113.  The  passivity  of  females,  114.  Males 
of  species  in  which  no  real  pairing  occurs  also  show  strik- 
ing secondary  sexual  characters,  114.  Necessity  of 
assuming  unproved  aesthetic  development  among  lower 
animals,  114.  Few  recorded  cases  of  observed  choosing 
by  female,  115.  Difficult  to  assume  utility  for  many 
secondary  sexual  characters,  115.  Stolzmann's  case  of  the 
Andean  humming-birds,  116.  How  explain  the  beginnings 
of  secondary  sexual  characters,  117.  How  explain  orna- 
mental characters  appearing  in  both  males  and  females, 
118.  Morgan's  objections  to  sexual  selection  theory,  118. 
Experimental  evidence  touching  the  theory  is  against  it, 
1 20.  Mayer's  experiments  with  Promethea  and  Porthetria 
moths,  121.  Douglass's  and  Diirigen's  observations  on 


CONTENTS. 

PAGE 

lizards,    123.     Substitutionary    theories  of    the   origin   of 
secondary  sexual  characters,  124. 

APPENDIX:  References  to  books  and  papers  discussing 
sexual  selection,  125.  Wolff's  critical  exposition  of  weak- 
nesses in  sexual  selection,  126. 

CHAPTER    VI. 

DARWINISM   DEFENDED       .        ...        .        .        .129 

Position  of  the  defenders  of  Darwinism,  129.  Reaction 
against  the  too  speculative  positions  of  Haeckel  and 
Weismann,  130.  "Haeckelismus,"  130.  Weismannism, 
131.  Struggle  between  Neo-Darwmians  and  Neo-La- 
marckians,  133.  Concessions  of  the  Neo-Darwinians,  134. 
Answer  to  objection  concerning  the  too  slight  character  of 
fluctuating  or  Darwinian  variations  to  serve  as  handles  for 
natural  selection,  138.  Answer  to  the  objection  concern- 
ing the  linear  and  quantitative  character  of  Darwinian 
variation,  139.  Answer  to  the  objection  that  selection  can- 
not produce  many-branched  descent,  142.  Answer  to  the 
statement  that  selection  can  produce  continuous  change 
or  evolution,  but  not  species,  143.  Answer  to  the  objec- 
tion concerning  the  production  by  selection  of  co-adaptive 
and  highly  complex  specialisations,  144.  Answer  to  the 
•objection  concerning  the  over-development  of  specialisa- 
tions, 146.  Discussion  of  the  difficulty  that  natural  selec- 
tion has  with  structural  degeneration,  146.  The  Darwinian 
answer  to  the  expressions  of  doubt  about  the  rigour  of 
selection,  148.  Answer  to  the  objections  to  the  sexual 
selection  theory,  148.  Discussion  of  the  objection  to  the 
derivation  of  evidence  for  natural  selection  from  the  facts 
of  artificial  selection,  150.  Tayler's  general  defence,  153. 
APPENDIX:  Weldon's  experiments  on  Carctnus,  158. 
Tayler's  explanation  of  degeneration  by  natural  selection, 
162.  Plate's  explanation  of  character  fixity  in  domestic 
animals,  163. 

CHAPTER    VII. 

DARWINISM  DEFENDED  (Continued)-.    PLATE'S   CON- 
CILIATORY  DEFENCE 164 

Plate,  a  fair-minded  Darwinian  champion,  164.  Answers 
to  the  objection  based  on  the  slight  character  and  inutility 
of  Darwinian  variations,  165.  Many  slight  differences  at 


CONTENTS.  ix 

PAGE 

first  glance  apparently  indifferent  in  character  found  on 
more  careful  inspection  to  be  of  advantage,  166.  Slight 
characters  aided  by  co-related  differences,  167.  The  prin- 
ciple of  the  change  of  function,  168.  Characters  of  in- 
different value  under  one  condition  of  environment, 
suddenly  made  important  by  a  change  in  life-conditions, 
169.  Organs  of  universal  character  which  can  become 
modified  in  various  directions,  169.  Lamarckian  factors 
called  to  the  aid  of  Darwinism,  170.  Answers  to  the 
objection  based  on  the  improbability  of  the  appearance  of 
the  right  variations  at  the  right  time  for  the  progressive 
perfecting  or  development  of  an  organ,  170.  Selection 
directs  itself  according  to  variation,  not  variation  accord- 
ing to  any  assumed  needs  of  selection,  171.  Selection 
works  with  plural  variations,  not  single  ones,  172.  The 
same  selective  value  can  often  be  attained  through  combi- 
nations of  various  peculiarities  and  the  same  effect 
reached  by  various  means,  172.  The  element  of  chance 
not  peculiar  to  the  Darwinian  explanation  of  co-adap- 
tations, 175.  Answers  to  the  objection  based  on  the 
assumed  improbability  that  during  the  course  of  the 
development  of  a  complex  organ  or  whole  body-part,  or 
during  the  perfecting  of  a  changing  adaptation  the 
numerous  necessary  adaptations  will  occur  in  such  a  suc- 
cessive series  as  to  make  possible  any  harmonious  correla- 
tion of  the  various  single  variations,  176.  Plate's  reliance 
on  the  Lamarckian  factor  of  the  inheritance  of  characters 
acquired  through  use,  disuse,  and  other  functional  stimuli, 
178.  The  attainment  of  selective  value  by  various  means, 
178.  Weismann's  theory  of  germinal  selection  unaccept- 
able, 180.  Weismann's  principle  of  amphimixis  of  great 
importance,  180.  The  necessity  of  concessions  admitted 
181.  The  necessity  of  invoking  auxiliary  or  aiding  prin- 
ciples to  support  the  natural  selection  theory,  182. 

APPENDIX:  Conn's  discussion  of  selective  value,  182. 
References  to  papers  on  correlation,  184.  Cope's  proof 
that  natural  selection  cannot  originate  new  characters,  185. 

CHAPTER    VIII. 

OTHER    THEORIES    OF    SPECIES-FORMING:     THEO- 
RIES AUXILIARY   TO   SELECTION     ....     187 

The  presentation  of  theories  to  aid  the  selection  theories 
or  others  to  replace  them  really  a  continuation  of  the 


CONTENTS. 

defence  of,  and  attack  on,  Darwinism,  187.  The  Weis- 
mannian  theories,  188.  Panmixia,  190.  The  theory  of 
germinal  selection,  193.  The  physical  and  chemical 
structure  of  protoplasm,  194.  Objections  to  the  theory 
of  germinal  selection,  200.  Roux's  theory  of  intra-selec- 
tion,  or  the  battle  of  the  parts,  201.  Objections  to  Roux's 
theory,  203.  The  theory  of  organic  selection,  or  ortho- 
plasy,  208. 

APPENDIX:  List  of  Weismann's  evolution  papers,  212. 
Theories  of  ultimate  protoplasmic  structure,  214.  Encase- 
ment theory,  215.  Micromeric  theories,  215.  Buffon's 
theory,  216.  Spencer's  theory,  217.  Darwin's  theory, 
218.  Nageli's  theory,  219.  De  Vries's  theory,  220.  Hat- 
schek's  theory,  222.  Delage's  criticisms,  224.  Le  Dantec's 
criticisms,  224.  Verworn's  biogen  hypothesis,  225.  De- 
lage's machine  theory,  225.  Le  Dantec's  theory  of 
chemism,  225.  Neo-vitalism,  226.  Morgan's  criticism  of 
Weismann's  method  of  argument,  229.  References  to 
discussions  of  orthoplasy,  229. 


PAGE 


CHAPTER   IX. 

OTHER  THEORIES  OF  SPECIES-FORMING  (Continued)'. 
THEORIES  AUXILIARY  TO  SELECTION  (Continued) 

Isolation  theories,  232.  Wagner's  "Separations-theorie," 
234.  Jordan's  upholding  of  the  importance  in  species- 
forming  of  geographic  isolation,  237.  Biologic  and  sexual 
isolation,  or  physiological  selection,  243.  Gulick's  work 
and  conclusions,  249. 

APPENDIX:  References  to  discussions  of  isolation,  253. 
Haacke's  summary  of  Wagner's  theory,  253.  Grinnell's 
studies  of  geographic  differences  in  the  chickadee,  255. 
Further  references  to  discussions  of  isolation,  261. 


232 


CHAPTER  X. 

OTHER  THEORIES  OF  SPECIES-FORMING  (Con- 
tinued)-.  THEORIES  ALTERNATIVE  TO  SELEC- 
TION   

Three  general  groups  of  theories  proposed  to  replace  the 
selection  theories  as  explanations  of  species-forming  and 
evolution,  262.  The  Lamarckian  theory,  262.  Objections 
to  the  Lamarckian  factors,  especially  that  of  the  inheritance 


262: 


CONTENTS.  xi 

PAGE 

of  acquired  characters,  266.  Great  use  could  be  made  of 
the  Lamarckian  factors  in  explaining  evolution  phenomena 
if  these  factors  could  be  given  validity,  271.  Orthogenesis 
and  determinate  variation,  pointing  toward  orthogenesis, 
271.  Nageli's  theory  of  orthogenesis,  277.  Eimer's  ortho- 
genetic  theory,  282.  Cope's  theory  of  bathmism  and 
kinetogenesis,  285.  Jaeckel's  theory  of  metakinesis,  289. 

APPENDIX:  References  to  Lamarck's  writings,  290.  Brown- 
Sequard's  experiments  on  guinea  pigs,  290.  Hyatt's 
studies  of  Planorbis,  295.  Fischer's  experiments  with 
butterflies,  296.  Experiments  with  silkworms,  298.  Ref- 
erences to  books  and  papers  on  inheritance  of  acquired 
characters,  305.  Redfield's  position,  305.  Montgomery's 
explanation  of  inheritance  of  variation,  306.  Scientific 
aspects  of  Burbank's  work,  310.  Orthogenetic  variation 
in  palaeontology,  319.  A  case  of  apparent  determinate 
variation,  319.  Pfeffer's  theory  of  orthogenesis,  320. 
Eimer's  theory  of  orthogenesis,  321.  Apparent  determi- 
nate evolution,  322.  Snodgrass's  observances  on  bills  of 
Galapagos  birds,  323.  Cope's  belief  in  orthogenetic  evolu- 
tion, 323.  Whitman's  belief  in  determinate  variation,  325. 
Cunningham  and  orthogenesis,  326. 


CHAPTER  XI. 

OTHER  THEORIES  OF  SPECIES-FORMING  (Con- 
tinued)-. THEORIES  ALTERNATIVE  TO  SELEC- 
TION (Continued)  .  . 327 

Heterogenesis  or  the  mutations  theory,  327.  Formula- 
tions of  heterogenesis  theories  by  von  Kolliker,  Dall, 
Galton,  and  Emery,  330.  Korschinsky's  heterogenesis 
theory,  333.  De  Vries's  mutations  theory,  337.  Present 
status  of  de  Vries's  theory,  348.  Alternative  theories  to 
explain  secondary  sexual  characters,  352. 

APPENDIX:  Mendel  and  his  work,  356.  References  to 
recent  work  on  Mendelism,  357.  Darwin's  examples  of 
race  origin  from  sports,  357.  A  recent  example  of  race 
origin  from  a  sport  in  cattle,  358.  Galton's  discussion  of 
specific  stability,  360.  References  to  discussions  by  de 
Vries  of  species-forming,  362.  American  opinions  of  the 
mutations  theory,  362.  Davenport's  example  of  species 
origin  by  slight  continuous  change,  367.  Merriam's  criti- 
cism of  the  mutations  theory,  367.  Plate's  criticism  of  the 


xii  CONTENTS. 

PAGE 

mutations  theory,  368.     References  to  theories  explaining 
secondary  sexual  characters,  373. 

CHAPTER  XII. 

DARWINISM'S  PRESENT  STANDING        ....     374 

Natural  selection  the  final  control  in  evolution,  but  not 
a  sufficient  explanation  of  species-forming,  374.  Weak- 
nesses of  the  substitutionary  theories,  375.  The  unknown 
factors  of  evolution,  377.  Prime  needs  of  evolution  study; 
first,  the  intensive  study,  statistical  and  experimental,  of 
variability,  378.  Second,  the  means  of  cumulating  varia- 
bility along  definite  lines,  379.  Third,  the  investigation  of 
adaptation,  380.  A  suggested  argument  for  a  belief  in  the 
transference  of  ontogenic  changes  into  phylogeny,  382.  A 
suggested  automatic  causal  factor  of  variability,  purposive 
but  not  purposeful,  384.  Our  present  ignorance  and  the 
call  to  work,  387. 

APPENDIX:  Wigand's  criticism  of  the  selection  theories, 
387.  Lankester's  upholding  of  Darwinism,  389.  De  Vries's 
discussion  of  species-forming  by  selection,  389.  Delage's 
estimate  of  selection,  390.  Osborn's  championship  of  the 
unknown  factors  of  evolution,  391.  Klebs's  conclusions 
from  experiments  on  plants,  392.  Friedlander's  discussion 
of  adaptation,  392.  Loeb's  attitude  toward  the  problem  of 
species-forming,  393. 

INDEX  .        .      '.  .        .        .        .        .        .        .    397 


DARWINISM   TO-DAY 


DARWINISM  TO-DAY. 


CHAPTER  I. 

INTRODUCTORY:  THE  "DEATH-BED  OF 
DARWINISM." 

"VoM  STERBELAGER  DES  DARWINISMUS  !"  This  is  the 
title  of  a  recent  pamphlet l  lying  before  me.  But  ever  since 
there  has  been  Darwinism  there  have  been  occasional  death- 
beds of  Darwinism  on  title  pages  of  pamphlets,  addresses, 
and  sermons.  Much  more  worth  consideration  than  any 
clerical  pamphlets  or  dissertations,  under  this  title,  by  frisch- 
gebackenen  German  doctors  of  philosophy — the  title  alone 
proving  prejudice  or  lack  of  judgment  or  of  knowledge — 
are  the  numerous  books  and  papers  which,  with  less  sensa- 
tional headlines  but  infinitely  more  important  contents,  are 
appearing  now  in  such  numbers  and  from  such  a  variety  of 
reputable  sources  as  to  reveal  the  existence  among  biologists 
and  philosophers  of  a  widespread  belief  in  the  marked 
weakening,  at  least,  if  not  serious  indisposition,  of  Darwin- 
ism. A  few  of  these  books  and  papers  from  scientific  sources 
even  suggest  that  their  writers  see  shadows  of  a  death-bed. 

The  present  extraordinary  activity  in  biology  is  two- 
phased  ;  there  is  going  on  a  most  careful  re-examination  or 
Modem  activ-  scrutmv  °f  tne  theories  connected  with  organic 
ity  in  biologic  evolution,  resulting  in  much  destructive  criti- 
cism of  certain  long-cherished  and  widely  held 
beliefs,  and  at  the  same  time  there  are  being  developed  and 
almost  feverishly  driven  forward  certain  fascinating  and 
fundamentally  important  new  lines,  employing  new  methods, 


2  DARWINISM   TO-DAY. 

of  biological  investigation.  Conspicuous  among  these  new 
kinds  of  work  are  the  statistical  or  quantitative  study  of 
variations  and  that  most  alluring  work  variously  called 
developmental  mechanics,  experimental  morphology,  ex- 
perimental physiology  of  development,  or,  most  suitably  of 
all  because  most  comprehensively,  experimental  biology.2 
This  work  includes  the  controlled  modification  of  conditions 
attending  development  and  behaviour,  and  the  pedigreed 
breeding  of  pure  and  hybrid  generations.  Now  this  combina- 
tion of  destructive  critical  activity  and  active  constructive  ex- 
perimental investigation  has  plainly  resulted,  or  is  resulting, 
in  the  distinct  weakening  or  modifying  of  certain  familiar 
and  long-entrenched  theories  concerning  the  causative  factors 
and  the  mechanism  of  organic  evolution.  Most  conspicuous 
among  these  theories  now  in  the  white  light  of  scientific 
scrutiny  are  those  established  by  Darwin,  and  known,  col- 
lectively, to  biologists,  as  Darwinism. 

To  too  many  general  readers  Darwinism  is  synonymous 
with  organic  evolution  or  the  theory  of  descent.    The  word 

is  not  to  be  so  used  or  considered.  Darwinism, 
winisufis,8*"  primarily,  is  a  most  ingenious,  most  plausible, 

and,  according  to  one's  belief,  most  effective  or 
most  inadequate,  causo-mechanical  explanation  of  adaptation 
and  species-transforming.  It  is  that  factor  which,  ever  since 
its  proposal  by  Darwin  in  1859,  has  been  held  by  a  majority 
of  biologists  to  be  the  chief  working  agent  in  the  descent, 
that  is,  the  origin,  of  species.  However  worthy  Darwin  is  of 
having  his  name  applied  directly  to  the  great  theory  of 
descent — for  it  was  only  by  Darwin's  aid  that  this  theory, 
conceived  and  more  or  less  clearly  announced  by  numerous 
pre-Darwinian  naturalists  and  philosophers,  came  to  general 
and  nearly  immediate  acceptance — the  fact  is  that  the  name 
Darwinism  has  been  pretty  consistently  applied  by  biologists 
only  to  those  theories  practically  original  with  Darwin  which 
offer  a  mechanical  explanation  of  the  accepted  fact  of 


INTRODUCTORY:   "DEATH-BED   OF    DARWINISM."       3 

descent.  Of  these  Darwinian  theories  the  primary  and  all- 
important  one  is  that  of  natural  selection.  Included  with 
this  in  Darwinism  are  the  now  nearly  wholly  discredited 
theories  of  sexual  selection  and  of  the  pangenesis  of  gem- 
mules.  It  may  also  be  fairly  said  that  the  theory  of  the 
descent  of  man  from  the  lower  animals  should  be  included  in 
Darwinism.  For  Darwin  was  practically  the  first  naturalist 
bold  enough  to  admit  the  logical  and  obvious  consequences 
of  the  general  acceptance  of  the  theory  of  descent,  and  to 
include  man  in  the  general  chain  of  descending,  or  ascend- 
ing, organisms.  So  that  the  popular  notion  that  Darwinism 
is  in  some  way  the  right  word  to  apply  to  the  doctrine  that 
man  has  come  from  the  monkeys  is  rather  nearer  right  than 
wrong.  But  biologists  do  not  recognise  the  descent  of  man 
as  a  special  phase  of  Darwinism,  but  rather  of  the  whole 
theory  of  descent,  or  organic  evolution. 

Darwinism,  then,  is  not  synonymous  with  organic  evolu- 
tion, nor  with  the  theory  of  descent  (which  two  phases  are 
.  .  used  by  the  biologist  practically  synonymously), 

not  synonymous  Therefore  when  one  reads  of  the  "death-bed  of 
with  evolution,  Darwinism,"  it  is  not  of  the  death-bed  of  or- 
ganic evolution  or  of  the  theory  of  descent  that  one  is  read- 
ing. While  many  reputable  biologists  to-day  strongly  doubt 
the  commonly  reputed  effectiveness  of  the  Darwinian  selec- 
tion factors  to  explain  descent — some,  indeed,  holding  them 
to  be  of  absolutely  no  species-forming  value — practically 
no  naturalists  s  of  position  and  recognised  attainment  doubt 
the  theory  of  descent.4  Organic  evolution,  that  is,  the 
descent  of  species,  is  looked  on  by  biologists  to  be  as  proved 
a  part  of  their  science  as  gravitation  is  in  the  science  of 
physics  or  chemical  affinity  in  that  of  chemistry.  Doubts 
of  Darwinism  are  not,  then,  doubts,  of  organic  evolution. 
Darwinism  might  indeed  be  on  its  death-bed  without  shaking 
in  any  considerable  degree  the  confidence  of  biologists  and 
natural  philosophers  in  the  theory  of  descent. 


4  DARWINISM   TO-DAY. 

But  the  educated  reader,  the  scientific  layman,  the  thinker 
and  worker  in  any  line  of  sociologic,  philosophic,  or  even 

theologic  activity  is  bound  to  be  disturbed  and 
Present-day  J 

anti-Darwin-  unsettled  by  rumours  from  the  camp  of  pro- 
um'  fessional  biologists  of  any  weakness  or  mortal 

illness  of  Darwinism.  We  have  only  just  got  ourselves  and 
our  conceptions  of  nature,  of  sociology  and  philosophy,  well 
oriented  and  adjusted  with  regard  to  Darwinism.  And  for 
relentless  hands  now  to  come  and  clutch  away  our  founda- 
tions is  simply  intolerable.  Zum  Teufel  with  these  German 
professors!  For  it  is  precisely  the  German  biologists  who 
are  most  active  in  this  undermining  of  the  Darwinian 
theories.  But  there  are  others  with  them ;  Holland,  Russia, 
Italy,  France,  and  our  own  country  all  contribute  their 
quota  of  disturbing  questions  and  declarations  of  protest 
and  revolt.  The  English  seem  mostly  inclined  to  uphold 
the  glory  of  their  illustrious  countryman.  But  there  are 
rebels  even  there.  Altogether  it  may  be  stated  with  full 
regard  to  facts  that  a  major  part  of  the  current  published 
output  of  general  biological  discussions,  theoretical  treatises, 
addresses,  and  brochures  dealing  with  the  great  evolutionary 
problems,  is  distinctly  anti-Darwinian  in  character.  This 
major  part  of  the  public  discussion  of  the  status  of  evolution 
and  its  causes,  its  factors  and  mechanism,  by  working 
biologists  and  thinking  natural  philosophers,  reveals  a 
lack  of  belief  in  the  effectiveness  or  capacity  of  the  natural 
selection  theory  to  serve  as  a  sufficient  causo-mechanical 
explanation  of  species-forming  and  evolution.  Nor  is  this 
preponderance  of  anti-Darwinian  expression  in  current 
biological  literature  to  be  wholly  or  even  chiefly  attributed 
to  a  dignified  silence  on  the  part  of  the  believers  in  selection. 
Answers  and  defences  have  appeared  and  are  appearing. 
But  in  practically  all  these  defences  two  characteristics  are 
to  be  noted,  namely,  a  tendency  to  propose  supporting 
hypotheses  or  theories,  and  a  tendency  to  make  certain 


INTRODUCTORY:   "DEATH-BED    OF   DARWINISM."       5 

distinct  concessions  to  the  beleaguering  party.  The  fair 
truth  is  that  the  Darwinian  selection  theories,  considered 
with  regard  to  their  claimed  capacity  to  be  an  independently 
sufficient  mechanical  explanation  of  descent,  stand  to-day 
seriously  discredited  in  the  biological  world.  On  the  other 
hand,  it  is  also  fair  truth  to  say  that  no  replacing  hypothesis 
or  theory  of  species-forming  has  been  offered  by  the  oppo- 
nents of  selection  which  has  met  with  any  general  or  even 
considerable  acceptance  by  naturalists.  Mutations  seem  to 
be  too  few  and  far  between;  for  orthogenesis  we  can  dis- 
cover no  satisfactory  mechanism;  and  the  same  is  true  for 
the  Lamarckian  theories  of  modification  by  the  cumulation,, 
through  inheritance,  of  acquired  or  ontogenic  characters.. 
Kurz  und  gut,  we  are  immensely  unsettled. 

Now  but  little  of  this  philosophic  turmoil  and  wordy- 
strife  has  found  its  way  as  yet'  into  current  American  litera- 
ture. Our  bookshop  windows  offer  no  display,  as  in  Ger- 
many, of  volumes  and  pamphlets  on  the  newer  evolutionary 
study;  our  serious-minded  quarterlies,  if  we  have  any,  and 
our  critical  monthlies  and  weeklies  contain  no  debates  or 
discussions  over  "das  Sterbelager  des  Darwinismus."  Our 
popular  magazines  keep  to  the  safe  and  pleasant  task  of 
telling  sweetly  of  the  joys  of  making  Nature's  acquaintance, 
through  field-glasses  and  the  attuned  ear.  But  just  as  cer- 
tainly as  the  many  material  things  "made  in  Germany"  have 
found  their  way  to  us  so  will  come  soon  the  echoes  and 
phrases  of  the  present  intellectual  activity  in  evolutionary 
affairs,  an  activity  bound  to  continue  as  long  as  the  new 
lines  of  biological  investigation  continue  their  amazing  out- 
put of  new  facts  to  serve  as  the  bases  for  new  critical  attacks 
on  the  old  notions  and  for  the  upbuilding  of  new  hypotheses. 
If  now  the  first  of  these  echoes  to  come  across  the  water 
to  us  prove  to  be,  as  wholly  likely,  those  from  the  more  vio- 
lent and  louder  debaters,  they  may  lead  to  an  undue  dismay 
and  panic  on  our  part.  Things  are  really  in  no  such  desper- 


6  DARWINISM   TO-DAY. 

ate  way  with  Darwinism  as  the  polemic  vigour  of  the  Ger- 
man and  French  anti-Darwinians  leads  them  to  suggest. 
Says  one  of  them  :5  "Darwinism  now  belongs  to  history, 

Intern  erate  ^e  that  other  curiosity  of  our  century,  the 
anti-Darwin-  Hegelian  philosophy ;  both  are  variations  on  the 
theme:  how  one  manages  to  lead  a  whole  gen- 
eration by  the  nose."  The  same  writer  also  speaks  of  "the 
softening  of  the  brain  of  the  Darwinians."  Another  one,8  in 
similarly  relegating  Darwinism  to  the  past,  takes  much  pleas- 
ure in  explaining  that  "we  [anti-Darwinians]  are  now  stand- 
ing by  the  death-bed  of  Darwinism,  and  making  ready  to 
send  the  friends  of  the  patient  a  little  money  to  insure  a 
decent  burial  of  the  remains."  No  less  intemperate  and  in- 
decent is  Wolff's  T  reference  to  the  "episode  of  Darwinism" 
and  his  suggestion  that  our  attitude  toward  Darwin  should 
be  "as  if  he  had  never  existed."  Such  absurdity  of  ex- 
pression might  pass  unnoticed  in  the  mouth  of  a  violent 
non-scientific  debater — let  us  say  an  indignant  theologian 
of  Darwin's  own  days — but  in  the  mouth  of  a  biologist  of 
recognised  achievement,  of  thorough  scientific  training  and 
unusually  keen  mind — for  this  expression  came  from  just 
:such  a  man — it  can  only  be  referred  to  as  a  deplorable 
•example  of  those  things  that  make  the  judicious  to  grieve. 
Such  violence  blunts  or  breaks  one's  own  weapons. 

While  I  have  said  that  the  coming  across  the  water  of 
the  more  vigorous  anti-Darwinian  utterances  might  cause 
some  dismay  and  panic  in  the  ranks  of  the  educated  reader — 
really  unnecessary  panic,  as  I  hope  to  point  out — it  will 
doubtless  occur  to  some  of  my  readers  to  say  that  this  fear 
of  panic  is  unwarranted.  If  the  first  phrases  to  come  are 
as  injudicious  and  intemperate,  hence  as  unconvincing,  as 
those  just  cited,  the  whole  anti-Darwinian  movement  will 
be  discredited  and  given  no  attention.  Which,  I  hasten  to 
reply,  will  be  as  much  of  a  mistake  as  panic  would  be. 
There  is  something  very  seriously  to  be  heeded  in  the 


INTRODUCTORY:   "DEATH-BED   OF   DARWINISM."       7 

chorus  of  criticism  and  protest,  and  wholly  to  stop  one's 
ears  to  these  criticisms  is  to  refuse  enlightenment  and  to 
show  prejudice.  I  have  thought  it,  therefore,  worth  while 
to  try  to  anticipate  the  coming  of  fragmentary 
thisbook°f  an(*  disturbing  extracts  from  the  rapidly  in- 
creasing mass  of  recent  anti-Darwinian  litera- 
ture by  presenting  in  this  book  a  summary  account  not  alone 
of  these  modern  criticisms,  but  of  the  answers  to  them  by  the 
steadfast  Darwinians,  and  of  the  concessions  and  supporting 
hypotheses  which  the  supporters  of  both  sides  have  been  led 
to  offer  during  the  debates.  I  shall  try  to  give  a  fair  state- 
ment of  the  recent  attacks  on,  and  the  defence  and  present 
scientific  standing  of,  the  familiar  Darwinian  theories,  and 
to  give  also  concise  expositions,  with  some  critical  comment, 
of  the  more  important  new,  or  newly  remodelled  alternative 
and  auxiliary  theories  of  species-forming  and  descent,  such 
as  heterogenesis,  orthogenesis,  isolation,  etc.,  and  an  esti- 
mate of  their  degree  of  acceptance  by  naturalists. 

APPENDIX. 

1  Dennert,  E.,  "Vom  Sterbelager  des  Darwinismus,"  Stuttgart, 
1903.  An  intemperate  and  unconvincing  but  interesting  brief  against 
Dennert'sin-  the  Darwinian  factors,  *'.  e.,  the  selection  theories,  in 
temperate  attack  evolution.  Author  fully  accepts  the  theory  of  descent, 
on  Darwinism,  but  m  no  degree  the  Darwinian  causal  explanation  of 
this  descent.  "Was  ich  in  diesen  Berichten  nachzuweisen  suche, 
ist  die  Tatsache,  dass  der  Darwinismus  nunmehr  bald  der  Ver- 
gangenheit,  der  Geschichte  angehort,  dass  wir  an  seinem  Sterbe- 
lager stehen  und  dass  auch  seine  Freunde  sich  eben  anschicken, 
ihm  wenigstens  noch  ein  anstandiges  Begrabnis  zu  sichern"  (p.  4). 
The  valuable  thing  about  the  paper  is  that  it  is  largely  given  to  a 
gathering  together  of  the  anti-Darwinian  opinions  and  declarations 
of  numerous,  mostly  well-known  and  reputably  placed  biologists. 
Some  of  these  declarations  are  interpreted  by  Dr.  Dennert  in  a  way 
that  would  probably  hardly  be  wholly  acceptable  to  the  declarers,  but 
for  the  most  part  the  anti-Darwinian  beliefs  of  these  biologists  are 
unmistakably  revealed  by  their  .own  words.  Among  the  biologists 
and  biological  philosophers  thus  agglomerated  into  the  camp  of 


8  DARWINISM   TO-DAY. 

anti-Darwinism  are  Wigand,  Haacke,  von  Sachs,  Goette,  Kor- 
schinsky,  Haberlandt,  Steinmann,  Eimer,  M.  Wagner,  von  Kolliker, 
Nageli,  Kerner,  F.  von  Wagner,  Fleischmann,  O.  Schultze,  O.  Hert- 
wig,  and  others.  This  list  includes  reputable  botanists,  zoologists, 
and  palaeontologists. 

2  For  a  recent  account  of  such  work,  see  Morgan,  T.  H.,  "Experi- 
mental Zoology,"   1907. 

8  A.  Fleischmann,  professor  of  zoology  in  the  University  of  Er- 
langen,  is  the  only  biologist  of  recognised  position,  of  whom  I  am 
An  anti-evolu-   aware,  who  publicly  declares  a  disbelief  in  the  theory 
tion  university      of  descent.     He   seems   to  base   his   disbelief   on   the 
biologist,  £act  that  the  phyletic  (genealogic)  series  in  numerous 

animal  groups  are  as  yet  unexplained.  See  his  book,  "Die  De- 
scendenztheorie,"  Leipzig,  1901.  "Allein  je  mehr  ich  mich  in  die 
vermeintlichen  Beweisgriinde  derselben  [the  theory  of  descent] 
vertiefte  und  durch  Spezialuntersuchungen  positive  Anhaltspunkte 
fur  die  Stammesverwandtschaft  der  Tiere  zu  gewinnen  suchte,  um 
so  klarer  stellte  sich  mir  die  Erkenntniss  heraus,  dass  jene  Theorie 
eben  doch  mehr  nur  ein  bestrickender,  Ergebnisse  und  Aufklarung 
vortauschender  Roman  sei,  als  eine  auf  positiven  Grundlagen  auf- 
gebaute  Lehre."  (From  the  preface  of  this  book). 

4  A  curious  attempt  to  formulate  a  scientific  theory  explaining 
the  conditions  as  we  know  them  in  the  world  of  life,  to  replace  the 
Priedmann's  theory  of  descent,  is  contained  in  a  recent  small  book 
theory  to  replace  called  "Die  Konvergenz  der  Organismen"  (1904), 
evolution  with  by  Hermann  Friedmann.  The  author  assumes  that  the 
diversity  of  organisms  is  the  primary  condition,  and 
that  their  similarity  has  been  brought  about  through  convergence,  as 
opposed  to  the  postulate  of  the  theory  of  descent  to  the  effect  that 
diversity  of  life  has  grown  out  of  primary  identity  or  homogeneity. 
I  quote  (p.  12)  as  follows  from  Friedmann :  "Diese  Annahme,  die  in 
dem  vorliegenden  Buch  vertreten  wird,  ist  folgendermassen  zu  erlau- 
tern.  Wir  gehen  von  dem  Hauptsatze  aus,  dass  das  Leben  immer  als 
ein  bestimmter,  unwandelbarer  Speziescharakter  auftritt.  Die  spezi- 
fisch  verschiedenen  Lebensformen  erscheinen  jedoch  einander 
angenahert,  bezw.  annaherbar,  durch  drei  (Teil-)  prinzipien,  von 
denen  das  Leben  beherrscht  wird:  Das  Prinzip,  vermoge  dessert 
spezifisch  verschiedene  Formen  solche  Ubereinstimmungen  auf- 
weisen,  die  wir  als  primargesetzliche  betrachten,  nennen  wir  das 
Prinzip  der  Homologie ;  als  einen  Ausfluss  des  Prinzips  der  Analo- 
gic bezeichnen  wir  diejenigen  Ubereinstimmungen,  die  unter  dem 
Einfliisse  gleichwirkender  ausserer  (mittelbar  oder  unmittelbar 
bewirkender  oder  selektiver)  Bedingungen  entstehen ;  und  wir 
erkennea  drittens  die  Macht  und  die  Tragweite  eines  Prinzips  der 


INTRODUCTORY:   "DEATH-BED   OF   DARWINISM."       9 

direkten  Konvergenz,  welches  das  Entstehen  von  Ubereinstim- 
mungen  zwischen  den  Genossen  einer  Biosphare  aus  psychischen 
Ursachen  bewirkt.  Die  drei  Prinzipien  bilden  die  Grtmdlage  der 
Konvergenztheorie." 

5  Driesch,  H.,  Biolog.  Centralb.,  v.  16,  p.  355,    1896. 

6  Dennert,  E.,  "Vom  Sterbelager  des  Darwinismus,"  p.  4,  1903. 

7  Wolff,  G.,  "Beitrage  zur  Kritik  der  Darwin'schen  Lehre,"  p.  54,, 
1898. 


CHAPTER  II. 

DARWINISM   AND   EVOLUTION    DEFINED   AND 

DISTINGUISHED. 

i 

OUR  manuals  of  zoology  and  botany  contain  the  names 

and  descriptions  of  about  400,000  living  species  of  animals 

and  200,000  living  species  of  plants.     There  are 

Possible          parts  of  the  earth  from  which  we  have  collected 

modes  of  origin  . 

of  diverse  plant    as  yet  only  a  few  kinds  of  animals  and  plants, 


merely  the  larger,  more  conspicuous  or  more 
abundant  kinds  ;  there  are  no  parts  of  the  earth 
from  which  we  are  not  constantly  receiving  reports  of  the 
discovery  of  "new"  species  —  new,  of  course,  simply  in  the 
sense  that  we  have  not  known  them  before.  It  is  wholly 
certain  that  the  number  of  different  species,  that  is,  kinds, 
of  living  organisms  must  number  millions  ;  various  guesses,1 
all  unimportant,  have  been  made.  Of  the  extinct  species, 
those  hosts  of  strange  denizens  of  our  changing  earth  in  the 
ages  gone,  the  number  of  recorded  forms  can  at  best  be  but 
the  veriest  fraction  of  the  grand  total  of  species  that  have 
actually  existed.  Now  all  these  millions  of  kinds  of  animals 
and  plants  can  have  had  an  origin  in  some  one  of  but  three 
ways  ;  they  have  come  into  existence  spontaneously,  they 
have  been  specially  created  by  some  supernatural  power,  or 
they  have  descended  one  from  the  other  in  many-branching 
series  by  gradual  transformation.  There  is  absolutely  no 
scientific  evidence  for  either  of  the  first  two  ways  ;  there  is 
much  scientific  evidence  for  the  last  way.  There  is  left  for 
the  scientific  man,  then,  solely  the  last;  that  is,  the  method 

10 


DARWINISM   AND   EVOLUTION    DEFINED.          n 

of  descent.     The  theory  of  descent  (with  which  phrase  or- 
ganic evolution  may  be  practically  held  as  a  synonym)   is, 
then,  simply  the   declaration  that  the  various 

delo^/defined      nvmg    as    we^    as    tne    nOW    extinct    Species    of 

organisms  are  descended  from  one  another  and 
from  common  ancestors.  It  is  the  explanation  of  the  origin 
of  species  accepted  in  the  science  of  biology.  (The  natural 
question  about  the  first  species  or  the  first  several,  if  they 
appeared  simultaneously,  will  receive  attention  later;  the 
theory  of  descent  explains  the  origin  of  kinds  of  life,  not. 
the  origin  of  life.)  If  such  a  summary  disposal  of  the 
theories  of  spontaneous  generation  and  divine  creation  is  too 
repugnant  to  my  readers  to  meet  with  their  toleration,  then, 
as  Delage  has  pertinently  said  in  connection  with  a  similar 
statement  in  his  great  tome  on  "Heredity,"  my  book  and  such 
readers  had  better  immediately  part  company;  we  do  not 
speak  the  same  language. 

The  theory  of  descent,  long  before  it  was  fully  set  forth 
by  Darwin  in  1858  together  with  a  definite  and  wholly 
Pre-Darwin-  plausfole  causo-mechanical  explanation  of  it, 
ian  recognition  had  been  foreshadowed  and  even  fairly  ex- 
plicitly formulated  by  various  philosophical 
naturalists;  among  others,  Goethe  (1790)  in  Germany, 
Erasmus  Darwin  (1794)  (grandfather  of  Charles  Darwin) 
in  England,  Lamarck  (1809)  very  definitely  in  France, 
Chambers  in  the  "Vestiges  of  the  Natural  History  of 
Creation"  (1844),  and  Wallace  (1858)  coincidently  with 
Darwin  himself  had  all  recognised  descent  as  the  only  pos- 
sible scientific  explanation  of  the  origin  of  species  and  had 
offered  explanations  of  the  causal  factors  of  this  descent. 
Even  in  the  far  older  writings  2  of  the  Greeks,  most  con- 
spicuously perhaps  in  the  pages  of  Aristotle  (350),  may  be 
found  phrases  and  pages  foreshadowing  those  of  Lamarck, 
Wallace,  and  Darwin.  But  it  was  not  until  Darwin  had 
backed  up  the  formulation  of  the  descent  theory  with  that 


12  DARWINISM   TO-DAY. 

wonderful    accumulation    of    illuminating    and    explaining- 
facts,  and  with  those  always  ingenious  but  ever  candid  and 
supremely  honest  tryings-on  of  the  theory  to  the  various 
fact-bodies,  that  the  Theory  of  Descent  began 
Theory  of        to  be  spelled  with  capital  letters  in  the  biological 

v!liditySbyen       creed'     Nor  was   'lt  merely  good-fortune  that 
Darwin,  led  to  the  quick  and  wide  acceptance  of  the 

theory  of  descent  when  proposed  by  Darwin, 
while  the  same  theory  when  proposed  twenty  years  earlier  by 
Lamarck  found  practically  only  rejection.  It  was  because 
to  the  old  descent  theory  the  new  Darwinian  theories  were 
added.  It  was  because  of  that  explaining  Darwinism,  which 
to-day  is  being  so  rigorously  re-examined  as  to  its  validity,, 
that  the  theory  of  descent  took  its  definite  place  as  the 
dominant  declaration  in  the  biological  credo. 

This  Darwinism  of  1858  and  1859  consisted  of  the  selec- 
tion theories ;  the  Darwinian  pangenesis  of  gemmules  theory 
was  a  product  of  ten  years  later.  It  was  the  first  of  the 
Darwinian  concessions  to  scientific  anti-Darwinism.  That 
is,  it  was  a  supporting  hypothesis  erected  to  strengthen  a 
foundation  which  was  being  weakened  by  the  enemy's 
attacks.  Curiously  enough  this  first  Darwinian  concession 
was  made  not  on  behalf  of  a  true  Darwinian  principle,  but 
for  the  sake  of  a  Lamarckian  principle  which  Darwin  had 
thought  necessary  to  include  in  his  general  conception  of  the 
transmission  of  variations.  Even  in  the  formulation  of  the 
true  Darwinism,  the  selection  theories,  there  must  also  be 
recognised  the  participation  of  other  minds  than  that  of 
Darwin.  Malthus,  who  wrote,  in  1826,  of  the  over-supply 
and  the  consequent  struggle  in  the  human  population  and 
undoubtedly  added  much  to  Darwin's  confidence  in  his  own 
conception  of  the  prodigality  of  production  and  the  necessary 
struggle  for  life  throughout  the  world  of  organisms,  and 
Wallace,  who  came  to  conclusions  practically  identical  with 
Darwin's  at  practically  the  same  time,  are  men  whose  names 


DARWINISM   AND   EVOLUTION   DEFINED.         13 

are  ever  to  be  associated  with  the  theory  of  over-production, 
struggle,  and  selection. 

Darwinism  may  be  defined,  then,  as  a  certain  rational, 
causo-mechanical  (hence,  non-teleologic)  explanation  of  the 
The  Bar-  origin  of  new  species.  The  Darwinian  explana- 
mtioT ofdJ-"  tion  rests  on  certain  observed  facts,  and  certain 
scent,  inductions  from  these  facts.  The  observed 

facts  are :  ( I )  the  increase  by  multiplication  in  geometrical 
ratio  of  the  individuals  in  every  species,  whatever  the  kind 
of  reproduction  which  may  be  peculiar  to  each  species, 
whether  this  be  simple  division,  sporulation,  budding,  par- 
thenogenesis, conjugation  and  subsequent  division,  or 
amphimixis  (sexual  reproduction)  ;  (2)  the  always  apparent 
slight  (to  greater)  variation  in  form  and  function  existing 
among  all  individuals  even  though  of  the  same  generation  or 
brood;  and  (3)  the  transmission,  with  these  inevitable 
slight  variations,  by  the  parent  to  its  offspring  of  a  form 
.and  physiology  essentially  like  the  parental.  The  inferred 
(also  partly  observed)  facts  are:  (i)  a  lack  of  room  and 
food  for  all  these  new  individuals  produced  by  geometrical 
multiplication  and  consequently  a  competition  (active  or 
passive)  among  those  individuals  having  any  cecologic  rela- 
tions to  one  another,  as,  for  example,  among  those  occupying 
the  same  locality,  or  needing  the  same  food,  or  needing  each 
other  as  food;  (2)  the  probable  success  in  this  competition 
of  those  individuals  whose  slight  differences  (variations) 
are  of  such  a  nature  as  to  give  them  an  advantage  over  their 
confreres,  which  results  in  saving  their  life,  at  least  until 
they  have  produced  offspring;  and  (3)  the  fact  that  these 
"saved"  individuals  will,  by  virtue  of  the  already  referred 
to  action  of  heredity,  hand  down  to  the  offspring  their 
advantageous  condition  of  structure  and  physiology  (at 
least  as  the  "mode"  or  most  abundantly  represented  condi- 
tion, among  the  offspring) . 

The  competition  among  individuals  and  kinds   (species) 


14  DARWINISM    TO-DAY. 

of   organisms   may   fairly   be   called   a   struggle.     This    is 
obvious  when  it  is  active,  as  in  actual  personal 

8e?eSleand  battling  for  a  Piece  of  food  or  in  attempts  to 
capture  prey  or  to  escape  capture,  and  less 
obvious  when  it  is  passive,  as  in  the  endurance  of  stress  of 
weather,  hunger,  thirst,  and  untoward  conditions  of  any 
kind.  The  struggle  is,  or  may  be,  for  each  individual 
threefold  in  nature :  ( I )  an  active  struggle  or  com- 
petition with  other  individuals  of  its  own  kind  for 
space  in  the  habitat,  sufficient  share  of  the  food,  and 
opportunity  to  produce  offspring  in  the  way  peculiar  and 
common  to  Its  species;  (2)  an  active  or  passive  struggle  or 
competition  with  the  individuals  of  other  species  which  may 
M  need  the  same  space  and  food  as  itself,  or  may  need  it  or 
its  eggs  or  young  for  food,  and  (3)  an  active  (or  more 
usually  passive)  struggle  with  the  physico-chemical  external 
conditions  of  the  world  it  lives  in,  as  varying  temperature 
and  humidity,  storms  and  floods,  and  natural  catastrophes 
of  all  sorts.  For  any  individual  or  group  of  individuals  any 
of  these  forms  of  struggle  may  be  temporarily  ameliorated, 
as  is  ( i )  the  intra-specific  struggle  among  the  thousands  of 
honey-bee  individuals  living  together  altruistically  in  one 
hive,  or  (2)  the  inter-specific  struggle  when  two  species 
live  together  symbiotically  as  the  hermit  crab  *  Eupagnrns 
and  the  sea-anemone  Podocoryne,  or  (3)  the  struggle 
against  untoward  natural  conditions  as  in  special  times  or 
places  of  highly  favourable  climate,  etc.  Or  for  any  indi- 
vidual or  group  of  individuals  all  forms  of  the  struggle  may 
be  coincidently  active  and  severe.  The  resultant  of  these 
existing  conditions  is,  according  to  Darwin  and  his  followers, 
an  inevitable  natural  selection  of  individuals  and  of  species. 
Thousands  must  die  where  one  or  ten  may  live  to  maturity 
(*.  e.,  to  the  time  of  producing  young).  Which  ten  of  the 
thousand  shall  live  depends  on  the  slight  but  sufficient  ad- 
vantage possessed  by  ten  individuals  in  the  complex  struggle 


DARWINISM   AND   EVOLUTION   DEFINED.          15 

for  existence  due  to  the  fortuitous  possession  of  fortunate 
congenital  differences  (variations).  The  nine  hundred  and 
ninety  with  unfortunate  congenital  variations  are  extin- 
guished in  the  struggle  and  with  them  the  opportunity 
for  the  perpetuation  (by  transmission  to  the  offspring)  of 
their  particular  variations.  There  are  thus  left  ten  to  re- 
produce their  advantageous  variations.  The  offspring  of 
the  ten  of  course  will  vary  in  their  turn,  but  will  vary  around 
the  new  and  already  proved  advantageous  parental  condi- 
tion :  among  the  thousand,  say,  offspring  of  the  original 
saved  ten  the  same  limitations  of  space  and  food  will  again 
work  to  the  killing  off  before  maturity  of  nine  hundred  and 
ninety,  leaving  the  ten  best  equipped  to  reproduce.  This 
repeated  and  intensive  selection  leads  to  a  slow  but  steady 
and  certain  modification  through  the  successive  generations 
of  the  form  and  functions  of  the  species ;  a  modification 
always  towards  adaptation,  towards  fitness,  towards  a 
moulding  of  the  body  and  its  behaviour  to  safe  conformity 
with  external  conditions.  The  exquisite  adaptation  of  the 
parts  and  functions  of  the  animal  and  plant  as  we  see  it 
every  day  to  our  infinite  admiration  and  wonder  has  all 
come  to  exist  through  the  purely  mechanical,  inevitable 
weeding  out  and  selecting  by  Nature  (by  the  environmental 
determining  of  what  may  and  what  may  not  live)  through 
uncounted  generations  in  unreckonable  time.  This  is  Dar- 
win's causo-mechanical  theory  to  explain  the  transformation 
of  species  and  the  infinite  variety  of  adaptive  modification. 
A  rigorous  automatic  Natural  Selection  is  the  essential  idea 
in  Darwinism,  at  least  in  Darwinism  as  it  is  held  by  the 
present-day  followers  of  Darwin. 

What  auxiliary  and  supporting  factors  Darwin  considered 
possibly  or  certainly  of  some  influence  or  effect  in  species- 
Artificial          forming  we   may   postpone   reference   to  until 
selection.  our  more  particular  examination  of  the  natural 

selection  theory  in  succeeding  chapters  of  this  book.     Simi- 


16  DARWINISM   TO-DAY. 

larly  we  may  postpone  any  immediate  reference  to  the  facts 
of  Artificial  Selection  (so  important  in  any  account  of  Dar- 
winism), that  process,  more  or  less  familiar  to  us  all, 
whereby  the  plant  and  animal  breeders  quickly  and  exten- 
sively modify  the  particular  species  with  which  they  deal  so 
as  to  produce,  to  order,  as  it  were,  manifold  new  kinds 
(races)  of  organisms.  Despite  the  complexity  of  methods 
used  in  artificial  selection,  due  to  the  combining  of  hybrid- 
isation, direct  modification  by  varying  nutrition,  grafting, 
budding,  etc.,  with  selection,  the  basic  and  all-important 
-essential  is  the  selecting  of  a  few  individuals,  namely,  those 
which  show  the  desired  variations,  to  live  long  enough  to 
produce  offspring,  and  the  killing  out  before  maturity  of  the 
thousands  of  individuals  that  show  unfortunate  variations : 
(unfortunate,  that  is,  from  the  breeder's  point  of  view). 
In  the  gardens  of  that  extraordinary  plant-breeder,  Luther 
Burbank,  in  California,  great  bonfires  of  discarded  seedlings 
•correspond  to  the  succumbing  of  the  thousands  in  field  and 
forest  in  the  natural  struggle  for  existence,  while  tenderly 
cared  for  little  rows  of  pots  contain  the  fortunate  few  which 
have  withstood  the  rigours  of  the  artificial  competition. 

A  part  of  Darwinism,  which  has  already  been  named  as 
such,  is  the  theory  of  Sexual  Selection;  but  the  details  of 
this,  too,  we  may  leave  unexplained  for  the 
moment  in  order  not  too  much  to  trouble  the 
reader  and  the  author,  whose  aim  just  now  is 
to  define  the  essential  thought  or  conception  in  Darwinism, 
and  to  distinguish  between  this  essential  Darwinism  and 
the  different  and  wholly  independent  theory  of  descent. 
Sexual  selection  is  one  of  Darwin's  supporting  theories 
which  has  nearly  gone  quite  by  the  board.  It  is  based  on  a 
postulated  particular  and  limited  kind  of  natural  selection, 
not  involving  determination  between  life  and  death,  but  a 
determination  between  going  childless  and  leaving  posterity, 
— which  is,  after  all,  the  essential  determination  in  general 


DARWINISM    AND   EVOLUTION    DEFINED.          17 

natural  selection.  But  the  assumed  choice  in  the  theory 
of  sexual  selection  has  a  much  less  mechanical  and  auto- 
matically working  basis,  involves  violent  assumptions  re- 
garding the  aesthetic  development  of  birds,  butterflies,  and 
spiders,  and  as  we  shall  later  see  was  one  of  the  first  of  Dar- 
winian outworks  to  be  sadly  breached  by  attack. 

I  hope  now  to  have  pointed  out  clearly  in  the  preceding 

paragraphs    the    real    distinction    between    the    theory    of 

descent   and   the   theory   of   natural    selection 

Theory  of  de-     (Darwinism).     The   bases,    consisting    of    ob- 
scent  and  the 

theory  of  natural  served  facts  and  logical  reasons,  of  the  selec- 
tion  theory>  have  been  given;  perhaps  it  were 
well  to  state  briefly  the  bases,  or  sources  of  the 
scientific  evidence  for  the  theory  of  descent.  This  evi- 
dence is  derived  from  three  chief  sources;  the  study  of  the 
comparative  anatomy  and  structural  homologies  of  organ- 
isms, the  study  of  the  prehistoric  animals  and  plants,  that 
is,  palaeontology  or  historical  geology,  and  the  study  of 
ontogeny,  or  embryology,  that  is,  the  development  of  in- 
dividual animals  and  plants.  The  homologies  or  structural 
correspondence,  in  gross  and  in  detail,  which  the  study  of 
animal  and  plant  comparative  anatomy  reveals  to  exist  in 
varying  degrees  among  living  and  extinct  kinds  of  organ- 
isms have  but  one  possible  scientific  explanation  :  an  explana- 
tion which  serves  at  once  to  account  for  the  existence  of 
this  correspondence  and  for  its  varying  degrees. 
This  exPlanation  is  community  of  ancestry,  the 
blood-relationship  of  organisms,  the  theory  of 
descent.  Similarly  the  facts  revealed  by  the  study  of 
palaeontology  are  explicable  wholly  satisfactorily  by  the 
theory  of  descent  and  in  no  single  definitive  instance  do  they 
contradict  it.  Finally,  the  facts  and  conditions  relating  to 
the  embryology  or  ontogeny  of  animals  and  plants  are 
similarly  wholly  in  consonance  with  the  theory  of  descent, 
although  the  brilliant  positive  evidence  for  the  theory  which 


i8  DARWINISM   TO-DAY. 

the  first  revealing  of  the  phenomena  of  ontogeny  led  bi- 
ologists to  expect  and  even  to  anticipate  has  confessedly  not 
been  forthcoming  in  that  overwhelming  measure  hoped  for. 
The  evidence  is  excellent  and  positive  and  there  is  much  of 
it,  but  the  proof  that  man  is  descended  from  a  fish  because 
he  has  gill-slits  at  one  period  in  his  individual  development 
is  not  of  the  sort  to  rely  on  too  confidently.  The  recapitula- 
tion theory  of  Fritz  Miiller  and  Haeckel  is  chiefly  con- 
spicuous now  as  a  skeleton  on  which  to  hang  innumerable 
exceptions.  But  the  scientific  evidence  for  descent  which 
embryology  offers  is  neither  weak  nor  slight;  it  is  only  less 
overwhelming  and  all-sufficient  than  its  too  sanguine  early 
friends  and  sponsors  attributed  to  it. 

The  specific  character  of  the  evidence  for  the  theory  of 
descent  derived  from  the  three  chief  sources  just  mentioned 
cannot  claim  our  attention  here.  Knowledge  of  it  is  cer- 
tainly the  attribute  of  all  educated  readers.  If  any  one 
should  desire  to  refresh  his  memory  of  it,  he  may  readily  do 
this  by  reading  his  Darwin,  or  Wallace,  or  Huxley,  Haeckel,, 
Spencer,  Weismann,  Romanes,  Marshall,  Cope,4  et  al. 
What  may  for  the  moment  detain  us,  however,  is  a  reference 
to  the  curiously  nearly  completely  subjective  character  of 
the  evidence  for  both  the  theory  of  descent  and  natural 
selection.  Biology  has  been  until  now  a  science  of  observa- 
tion ;  it  is  beginning  to  be  one  of  observation  plus  experiment. 
The  evidence  for  its  principal  theories  might  be  expected  to 
be  thoroughly  objective  in  character;  to  be  of  the  nature  of 
positive,  observed,  and  perhaps  experimentally  proved,  facts. 
How  is  it  actually?  Speaking  by  and  large  we  only  tell 
the  general  truth  when  we  declare  that  no  indubitable  cases 
of  species-forming  or  transforming,  that  is,  of  descent,  have 
been  observed ;  and  that  no  recognised  case  of  natural  selec- 
tion really  selecting  has  been  observed.  I  hasten  to  repeat 
the  names  of  the  Ancon  sheep,  the  Paraguay  cattle,  the 
Porto  Santo  rabbit,  the  Artemias  of  Schmankewitch,  and 


DARWINISM   AND  EVOLUTION   DEFINED.          19 

the  de  Vriesian  evening  primroses  to  show  that  I  know  my 
list  of  classic  possible  exceptions  to  this  denial  of  observed 
species-forming,  and  to  refer  to  Weldon's  broad-and 
narrow-fronted  crabs  as  a  case  of  what  may  be  an  observa- 
tion of  selection  at  work.  But  such  a  list,  even  if  it  could 
be  extended  to  a  score,  or  to  a  hundred,  of  cases,  is  ludicrous 
as  objective  proof  of  that  descent  and  selection,  under 
whose  domination  the  forming  of  millions  of  species  is  sup- 
posed to  have  occurred.  The  evidence  for  descent  is  of 
satisfying  but  purely  logical  character;  the  descent  hypoth- 
esis explains  completely  all  the  phenomena  of  homology,  of 
palasontological  succession,  of  ontogeny,  and  of  geographi- 
cal distribution;  that  is,  it  explains  all  the  observed  facts 
touching  the  appearance  in  time  and  place  on  this  earth  of 
organisms  and  the  facts  of  their  likenesses  and  unlikenesses 
to  each  other,  and  this  no  other  theory  does.  The  evidence 
for  the  selection  theory  we  shall  refer  to  in  detail  in  the  suc- 
ceeding chapters,  so  we  may  merely  recall  now  that  it  also 
chiefly  rests  on  the  logical  conclusion  that  under  the 
observed  fact  of  over-production,  struggle  is  bound  to 
occur;  that  under  the  observed  fact  of  miscellaneous  varia- 
tion, those  individuals  most  fortunate  in  their  variations  will 
win  in  the  struggle;  and,  finally,  that  under  the  observed 
fact  of  heredity,  the  winners  will  transmit  to  their  posterity 
their  advantageous  variations,  all  of  which  inter-acting  facts 
and  logically  derived  processes  will  be  repeated  over  and 
over  again,  with  the  result  of  slow  but  constant  modification 
of  organic  types,  that  is,  formation  of  new  species.  In  the 
light  of  this  subjective  character  of  the  evidence  for  descent 
and  selection,  it  is  with  unusual  interest  that  one  notes  the 
swift  development  of  experimental  and  statistical  investiga- 
tion in  biology.  Experiment  and  statistics  are  capable  of 
mathematical  treatment;  biology  may  become  an  exact 
science  instead  of  one  solely  of  observation  and  induction. 
As  with  the  conclusion  of  this  chapter  we  are  practically 


20  DARWINISM   TO-DAY. 

to  conclude  all  reference  to  the  theory  of  descent,  which  is 
to-day  more  than  ever  before  an  integral  and  unquestioned 
part  of  biological  science,  and  to  devote  most  of  the  rest  of 
our  discussion  to  the  theory  of  natural  selection,  which 
is  to-day  being  subjected  to  more  searching  scientific  criticism 
than  ever  before  since  its  proposal  by  Darwin,  it  will  be  well 
to  distinguish,  if  we  can,  in  the  general  influence  that  post- 
Darwinian  biology  has  had  on  associated  sciences  and 
disciplines,  that  particular  influence  which  each  of  these  two 
great  theories  has  had.  So  that  if  our  faith  in  either  is  to 
be  shaken  we  may  recognise  what  effects  on  our  sociologic, 
pedagogic,  and  philosophic  beliefs  this  particular  weakening 
of  the  biologic  basis  may  have. 

The  relation  of  theology  T>  to  biology  is  concerned  almost 

wholly  with  the  theory  of  descent.    The  slow  and  gradual 

forming  of  species  including  the  particular  one, 

Eelationof       man,  and  their  genetic  relationship,  the  allying 

toSb^and11  of  man  by  blood  with  the  lower  animals— these 
philosophy,  are  the  two  biological  conceptions  (both  in- 
cluded in  the  descent  theory)  which  have  been 
the  chief  points  of  attrition  in  the  coming  together  of 
theology  and  biology.  Darwinism  specifically  as  such,  that 
is,  the  selection  principle,  has  had  some  special  attention  from 
theologians  because  of  its  substitution  of  a  causo-mechanical 
for  a  teleological  explanation  of  species-forming,  and  because 
it  differs  in  its  interpretation  of  the  time  necessary  for  peopling 
the  globe  with  a  variety  of  organic  forms  from  the  inter- 
pretation, or  rather  explicitly  specific  statement,  of  the  first 
chapter  of  Genesis.  But  on  the  whole  the  Darwinian  selec- 
tion theories  could  be  utterly  done  away  with  without  making 
any  appreciable  change  in  the  existing  relation  between 
theology  and  biology.  Huxley  said  this  to  the  theologian 
Darwinophobes  many  years  ago. 

And   practically   so  with  philosophy.6     It   is   the  trans- 
formation principle,  the  principle  of  continuity,  of  monism 


DARWINISM   AND   EVOLUTION   DEFINED.          21 

in  Nature  that  Evolution  represents,  that  philosophy  is  con- 
cerned to  consider.  Not  the  actual  how  of  the  modification 
and  transformism  of  animal  and  plant  life. 

In    pedagogy   it   is    also   the   theory   of   descent    rather 
than  the  selection  theory  which  has  been  drawn  on   for 
some  rather  remarkable  developments  in  child- 
Relation  of       study  and  instruction.     Unfortunately  it  is  ex- 
theory  of  descent  e  .         * 
to  pedagogy,        actly  on  that  weakest  of  the  three  foundation 

pillars  of  descent,  namely,  the  science  of  em- 
bryology with  its  Miillerian-Haeckelian  recapitulation  theory 
or  biogenetic  law,  that  the  child-study  pedagogues  have 
builded.  The  species  recapitulates  in  the  ontogeny  (develop- 
ment) of  each  of  its  individuals  the  course  or  history  of  its 
phylogeny  (descent  or  evolution).  Hence  the  child  corre- 
sponds in  different  periods  of  its  development  to  the  phyletic 
stages  in  the  descent  of  man.  As  the  child  is  fortunately 
well  by  its  fish,  dog,  and  monkey  stages  before  it  comes  into 
the  care  of  the  pedagogue,  he  has  to  concern  himself  only 
with  its  safe  progress  through  the  various  stages  of  pre- 
historic and  barbarous  man.  Detect  the  precise  phyletic 
stage,  cave-man,  stone-age  man,  hunter  and  roamer,  pastoral 
man,  agriculturalist,  and  treat  with  the  little  barbarian  ac- 
cordingly! What  simplicity!  Only  one  trouble  here  for 
the  pedagogue ;  the  recapitulation  theory  is  mostly  wrong ; 
and  what  is  right  in  it  is  mostly  so  covered  up  by  the 
wrong  part,  that  few  biologists  longer  have  any  confidence 
in  discovering  the  right.  What  then  of  our  generalising 
friends,  the  pedagogues? 

Finally  in  sociology,7  more  particularly  biological  soci- 
ology.    Here  again,  to  my  eyes,  much  biological  sociology 

rests  on  two  very  insecure  bases :   ( I )   a  too 

Relation  of       slight  acquaintance  with  biology  on  the  part 

to  sociology,        of    the    biological    sociologist,    and,     (2)     an 

acceptance  of,  and  confidence  in,  certain  biologi- 
cal theories  which  are  certainly  unwarranted,  and  are  not 


22  DARWINISM   TO-DAY. 

at  all  shared  by  the  biologists  themselves.  Biological  science 
contains  much  that  is  proved  and  certain;  but  also  much 
that  is  nothing  more  than  working  hypothesis,  provisional 
theory,  and  anticipatory  generalisation.  As  the  proved  part 
is  largely  of  the  nature  of  facts  of  observation,  isolated  and 
unrelated,  and  the  unproved  part  is  composed  of  the  large 
and  sweeping  generalisations,  the  plausible,  provisional  ex- 
planations, such  as  the  various  theories  of  heredity,  of  the 
results  of  struggle,  of  the  development  of  mutual  aid,  etc., 
that  is,  is  exactly  the  sort  of  material  that  the  sociologist 
needs  to  weave  into  his  biological  foundations  for  the 
sociologic  study  of  man,  it  is  exactly  this  unproved  part  of 
biology  that  the  searching  sociologist  carries  home  with  him 
from  his  excursions  into  the  biological  field.  The  recapitula- 
tion theory  looms  up  large  and  familiar  in  biological  soci- 
ology; it  is  mostly  discredited  in  biology.  The  inheritance 
of  acquired  characters  serves  as  basis  for  much  sociology; 
most  biologists  believe  it  impossible.  The  selection  theories 
are  gospel  to  some  sociologists ;  they  are  the  principal  moot 
points  in  present-day  biology.  And  so  on.  Biology  is  not 
yet  come  to  that  stage  in  its  development  where  it  can  offer 
many  solidly  founded  generalisations  on  which  other  sciences 
can  build.  The  theory  of  descent  is  one  such  safe  great 
generalisation;  but  perhaps  Darwinism  is  not  another.  At 
least  many  scholars  do  not  believe  that  it  is. 

APPENDIX. 

1  For  the  insects  alone  entomologists  have  estimated,  on  a  basis 
of  the  numbers  of  new  species  being  annually  found  and  described, 
and  on  the  basis  of  the  degree  to  which  the  entomological  explora- 
tion of  the  earth  has  been  carried,  that  over  two  million  species 
must  be  in  present  existence. 

2  See  H.  F.  Osborn's  "From  the  Greeks  to  Darwin"  (1895)  for  a 
_.  ,       careful  history  of  the  unfolding  of  the  descent  idea; 

scent  theory,         see  a^so  Edgar  Dacque.  "Der  Descendenzgedanke  und 

seine  Geschichte,"  1903;  also  Carus,  J.  V.,  "Geschichte 

der  Zoologie  bis  auf  J.  Muller  und  C.  Darwin,"  1872;  also  Clodd, 


DARWINISM    AND    EVOLUTION    DEFINED.          23 

Edw.,  "Pioneers  of  Evolution  from  Thales  to  Huxley,"  1897; 
and  Quatrefages,  A.  de,  "Les  fimules  de  Darwin,"  2  vols.,  1894. 

3  Many  of  the  hermit  crabs    (Paguridae)    which  live  in  the  dis- 
carded shells  of  gasteropod  molluscs  have  some   species   of   small 
colonial  polyp,  as  Podocoryne,  attached  to  and  partly  covering  the 
shell.    The  polyp  colony  profits  by  being  carried  about  and  by  obtain- 
ing bits  of  food  when  the  crab  has  succeeded  in  catching  prey  and 
is  tearing  it  to  pieces  with  his  claws,  while  the  crab  profits  by  the 
protection  afforded  it  by  the   stinging  threads  and  nettle  cells   of 
the  polyp.     Esig  saw   in   the  aquaria  of  the  zoological   station   at 
Naples  a  small  octopus  which  was  trying  to  insert  one  of  its  ten- 
tacles into  a  shell  to  get  the  crab,  quickly  driven  away  by  the  many 
stinging  threads  with  which  it  was  caressed  by  the  polyp  colony 
seated  on  the  outer  surface  of  the  shell.    This  symbiotic  life  between 
hermit  crab  and  polyp  goes  so  far  with  some  species  that  the  hermit 
crabs  never  rest  until  they  have  a  polyp  colony  seated  on  their  shell. 

4  Among  more   recent  books  stating  the  essential  points  in   this 
evidence  may  be  mentioned  Conn's  "Evolution  of  To-day,"    1889; 

Books  giving  Wallace's  "Darwinism,"  1891 ;  A.  M.  Marshall's 
the  evidences  for  "Lectures  on  the  Darwinian  Theory,"  1894;  Ro- 
descent,  manes's  "Darwin  and  After  Darwin,"  Vol.  I,  1896; 

Klaatsch's  "Grundziige  der  Lehre  Darwins,"  1900;  Metcalfs  "Out- 
line of  the  Theory  of  Organic  Evolution,"  1904;  Weismann's 
"Vortrage  iiber  Descendenztheorie,"  2  vols.,  1902;  Eng.  trans.  2 
vols.,  1904;  Lotsy,  J.  P.,  "Vorlesungen  iiber  Descendenztheorien, 
mit  besonderer  Beriicksichtigung  der  botanischen  Seite  der  Frage," 
2  vols.,  Vol.  I,  1906;  Jordan  and  Kellogg,  "Evolution  and  Animal 
Life."  1907. 

5  For  an  interesting  discussion  from  the  modern  point  of  view  of 
the  relation  between  Darwinian  biology  and  theology  see  Haeckel, 

Discussions  of  Ernst,  "Der  Monismus  als  Band  zwischen  Religion 
relation  of  de-  und  Wissenschaft,"  1893;  also  Vetter,  Benjamin, 
scent  and  the-  "Die  moderne  Weltanschauung  und  der  Mensch," 
0  °sy<  1903 ;  also  Wasmann,  Erich,  "Die  moderne  Biologic 

und  die  Entwicklungstheorie,"  1904.  (Author  is  a  Jesuit  priest  whose 
remarkable  studies  on  ants  and  their  messmates  have  made  him  well 
known  to  biologists.  He  accepts  the  theory  of  descent,  with  the  ex- 
clusion of  man  from  the  evolution  series.)  See  also  Hutton,  F.  W., 
"The  Lesson  of  Evolution,"  1902.  In  this  book  the  author  takes  a 
strong  stand  for  dualism,  making  the  point  that  the  theory  of  evo- 
lution has  rescued  philosophy  from  a  rigidly  monistic  materialistic 
basis  (a  mind-in-all-matter  theory),  and  has  made  necessary  a  dual- 
istic  theory  (mind-and-matter  theory)  because  of  the  necessity  of 
postulating  the  beginning  of  life  and  a  beginning  of  mind.  The 


24  DARWINISM    TO-DAY. 

theory  of  evolution  rescues  religion  from  Pantheism,  and  puts  it  on  a 
Theistic  basis.  "It  is  true,  as  Pantheists  urge,  that  their  only  experi- 
ence of  mind  is  in  connection  with  matter,  but  so  far  as  we  know 
mind  is  connected  only  with  one  kind  of  matter  called  protoplasm, 
which  cannot  possibly  exist  throughout  the  universe.  Consequently 
mind  must  either  be  absent  in  large  portions  of  matter  or  it  must 
be  associated  with  that  matter  in  some  way  which  quite  transcends 
their  experience.  So  that  we  have  no  more  experience  of  mind 
universally  distributed  through  matter  than  we  have  of  mind  dis- 
tinct from  matter.  And  the  argument  for  Pantheism  breaks  down." 
See  also  Le  Conte,  Jos.,  "Evolution,  its  Nature,  its  Evidences  and 
its  Relation  to  Religious  Thought,"  1891. 

6  Of  course  many  books  and  papers  concerning  the  relation  of 
biology  to  philosophy  have  been  written.     A  good  introduction  to 

Discussions  of  the  subJect  is  Eugen  Dreher's  "Der  Darwinismus  und 
relation  of  biol-  seine  Stellung  in  der  Philosophic,"  1877;  see  also  Ver- 
ogy  and  philoso-  worn,  Max,  "Naturwissenschaft  und  Weltanschauung," 
phy'  1904;  also  Adickes,  Erich,  "Kant  contra  Haeckel," 

1901 ;  also  Emil  du  Bois-Reymond's  "Uber  die  Grenzen  des  Naturer- 
kennens,"  and  "Die  Sieben  Weltrathsel" ;  also  Haeckel's  "Die  Welt- 
rathsel" (trans,  in  English  as  "The  Riddle  of  the  Universe")  ;  see 
also  Schurman,  J.  G.,  "The  Ethical  Import  of  Darwinism,"  1888; 
also  Huxley,  "Evolution  and  Ethics  and  Other  Essays,"  1894;  see 
also  Reinke,  J.,  "Einleitung  in  die  Theoretische  Biologic,"  1901. 
The  author  sets  out  in  this  book  the  philosophic  notions  of  Hart- 
mann,  Lotze,  Wundt,  Miiller  and  others  concerning  the  principles 
and  laws  of  biology,  and  does  this  definitely  enough  to  make  his 
book  a  pretty  good  compend  of  philosophico-biology. 

7  See*  Herbert  Spencer's  "Principles  of  Sociology" ;  also  Lester 
Ward's  "Biological  Sociology";  also  Benjamin  Kidd's  "Social  Evo- 

.p.  ,       lution" ;  also   Curt  Michaelis,   "Prinzipien  der  natiir- 

sociology,  lichen  und  sozialen  Entwicklungsgeschichte  des  Men- 

schen,"    1904;    also   "Darwinismus   und    Sozialwissen- 

schaft,"  1903;    see  also  Schallmeyer,  W.,  "Vererbung  und  Auslese 

in  Lebenslauf  der  Volker,"  1903. 

*  The  books  and  papers  referred  to  in  notes  5,  6,  and  7  are  simply 
certain  ones  that  have  particularly  interested  the  author.  The  lists 
of  references  make  not  the  slightest  pretence  to  guide  the  general 
reader  interested  in  these  special  subjects. 


CHAPTER  III. 
DARWINISM  ATTACKED. 

ATTACKS  on  Darwinism  have  been  made,  of  course,  ever 
since  there  was  any  Darwinism  to  attack.  In  those  first  days 
(and  months  and  years)  after  the  "Origin  of 
SPecies"  was  published  there  were  the  liveliest 
of  times  for  Darwin  and  his  supporters;  or 
rather  chiefly  for  the  supporters.  Darwin  wisely  kept 
aloof  from  the  debates.  But  for  the  first  band  of  followers 
with  the  indefatigable,  the  brilliant,  and  wholly  competent 
Huxley  at  its  head,  there  was  no  lack  of  opportunities  for 
jousting.  The  issue  was  never  doubtful;  Huxley  and  his 
informed  and  equipped  scientific  companions  against  the 
scientifically  ignorant,  angry,  incautious,  and  dogmatic 
Bishop  Wilberforces  had  unfair  odds.  The  victory  came 
swiftly  and  brilliantly  to  the  Darwinians.  At  this  time  there 
was  little  distinction  made  between  Darwinism  and  Evolu- 
tion. It  was  really  a  battle  by  the  theologians  against  the 
theory  of  descent.  And  the  theory  of  descent  was,  and  is, 
invulnerable. 

Since  those   warring   days   of   the    '6o's   the   theory   of 

descent  has  been  assailed  no  more,  that  is  in  any  important 

or  even  interesting  way.    And  the  true  Darwin- 

endfi^cSism"  ism'  tlie  selection  doctrine,  has  also  been  sub- 
of  Darwinism,  ject  to  no  conspicuous  and  popularly  recognised 
attack.  The  educated  public  accepted  the  re- 
sults of  the  first  battle  as  .final,  and  it  quietly  began  to 
rearrange  its  thought  and  to  some  degree  its  actual  ways 

25 


^6  DARWINISM   TO-DAY. 

of  living  in  accordance  with  these  newly  discovered  condi- 
tions of  life.  Nevertheless  there  has  been  from  the  day 
of  the  close  of  the  great  first  battle  to  the  present  moment  a 
steady  and  cumulating  stream  of  scientific  criticism  *  of  the 
Darwinian  selection  theories.  In  the  last  few  years,  it  has, 
as  already  mentioned  in  the  preface  and  introductory  chapter 
of  this  book,  reached  such  proportions,  such  strength  and 
•extent,  as  to  begin  to  make  itself  apparent  outside  of  strictly 
biological  and  naturo-philosophical  circles.  Such  older 
biologists  and  natural  philosophers  as  von  Baer,  von  Kolli- 
ker,  Virchow,  Nageli,  Wigand,  and  Hartmann,  and  such 
others  writing  in  the  nineties  and  in  the  present  century  as 
Ton  Sachs,  Eimer,  Delage,  Haacke,  Kassowitz,  Cope, 
Haberlandt,  Henslow,  Goette,  Wolff,  Driesch,  Packard, 
Morgan,  Jaeckel,  Steinmann,  Korschinsky,  and  de  Vries, 
are  examples  which  show  the  distinctly  ponderable  char- 
acter of  the  anti-Darwinian  ranks.  Perhaps  these  names 
mean  little  to  the  general  reader ;  let  me  translate  them  into 
the  professors  of  zoology,  of  botany,  of  palaeontology,  and 
of  pathology,  in  the  universities  of  Berlin,  Paris,  Vienna, 
Strassburg,  Tubingen,  Amsterdam,  Columbia  University, 
etc.  Now  without  knowing  the  man  personally,  or  even 
through  his  particular  work,  the  general  reader  can  safely 
attribute  to  men  of  such  position  a  certain  amount  of 
scientific  training,  of  proved  capacity,  and  of  special  ac- 
quaintanceship with  the  subject  of  their  discussion.  One 
does  not  come  to  be  a  professor  of  biology  in  Berlin  or 
Paris  or  Columbia  solely  by  caprice  of  ministers  of  educa- 
tion or  boards  of  trustees;  one  has  proved  one's  competency 
for  the  place.  To  working  biologists  the  names — I  have 
given,  of  course,  only  a  selection,  and  one  particularly  made 
to  show  variety  of  interest  (botany,  zoology,  palaeontology, 
pathology) — mean  even  more  than  the  positions.  They  are 
mostly  associated  with  recognised  scientific  attainment  and 
.general  intellectual  capacity. 


DARWINISM   ATTACKED.  27 

Among  the  critics  of  the  selection  theories  we  must  note 

two  groups,  differing  in  the  character  of  their  criticism 

,   more  in  degree  than  in  kind,  perhaps,  but  still 

Two  groups  of  ' 

scientific  at-  importantly  differing.  One  group  denies  in 
toto  any  effectiveness  or  capacity  for  species- 
forming  on  the  part  of  natural  selection,  while  the  other 
group,  a  larger  one,  sees  in  natural  selection  an  effective 
factor  in  directing  or  controlling  the  general  course  of 
descent,  holding  it  to  adaptive  lines,  but  denies  it  outright 
any  such  Allmacht  of  species  control  as  the  more  eager 
selectionists,  the  so-called  neo-Darwinians  or  Weismann- 
ians,  credit  it  with.  This  larger  group  of  critics  sees  in 
natural  selection  an  evolutionary  factor  capable  of  initiating 
nothing,  dependent  wholly  for  any  effectiveness  on  some 
primary  factor  or  factors  controlling  the  origin  and  direc- 
tion of  variation,  but  wholly  capable  of  extinguishing  all 
unadapted,  unfit  lines  of  development,  and,  in  this  way,  of 
exercising  decisive  final  control  over  the  general  course  of 
descent,  i.  e.,  organic  evolution.  Another  classification  of 
critics  may  be  made  on  the  basis  of  pure  destructiveness  on 
the  one  hand  as  opposed  to  destructiveness  combined  with 
constructiveness  on  the  other.  That  is,  some  critics  of  selec- 
tion, as  Wolff,  Pfeffer,  Driesch,  et  al.,  are  content  with  doing 
their  best  to  reveal  the  incapacity  of  Darwinism ;  others, 
on  the  contrary,  come  with  certain  more  or  less  well-outlined 
substitutionary  theories  in  their  hands.  Eimer  with  his 
theory  of  orthogenesis,  and  Korschinsky  and  de  Vries  with 
their  theory  of  mutations,  are  examples  of  the  latter  class. 
The  general  impression  left  on  one  after  a  considerable 
course  of  anti-Darwinian  reading  ranging  all  the  way  from 
the  extreme  attitude  and  the  violence  of  Den- 
attacknfndweak.nert'  Fleischmann,  Wolff,  and  Coe,  to  the 
ness  in  snbstitn-  tempered  and  reserved  criticism  of  Delage  and 
de  Vries,  is  that  there  is  a  very  real  and  effective 
amount  of  destructive  criticism  for  Darwinians  to  meet ;  and 


28  DARWINISM   TO-DAY. 

at  the  same  time  a  curious  paucity  of  satisfactory  or  at  all 
convincing  substitutionary  theory  offered  by  the  anti- 
Darwinians  to  replace  that  which  they  are  attempting  to 
dethrone.  The  situation  illustrates  admirably  the  varying 
worth  of  a  few  facts.  A  few  stubborn  facts  of  the  wrong 
complexion  are  fatal  things  for  a  theory ;  they  are  immensely 
effective  offensive  weapons.  But  these  same  few  facts  make 
a  pitiable  showing  when  they  are  called  on  to  support  a 
theory  of  their  own.  It  was  exactly  the  greatest  part  of 
Darwin's  greatness,  it  seems  to  me,  that  he  launched  his 
theory  only  after  making  the  most  remarkable  collection  of 
facts  yet  gathered  together  in  biological  science  by  any  one 
man.  Testing  his  theory  by  applying  to  it  successively 
fact  after  fact,  group  after  group  and  category  after  category 
of  facts,  he  convinced  himself  of  the  theory's  consonance 
with  all  this  vast  array  of  observed  biological  actuality. 
Compare  the  grounding  of  any  of  the  now  offered  replacing 
theories  with  the  preparation  and  founding  of  Darwinism. 
In  1864  von  Kolliker,2  a  great  biologist,  convinced  of  the 
incapacity  of  natural  selection  to  do  the  work  assigned  it  by 
its  founders  and  friends,  suggested  a  theory  of  the  origin  of 
species  by  considerable  leaps;  in  1899,  Korschinsky,3  on  the 
basis  of  some  few  personal  observations  and  the  compiling 
of  some  others,  definitely  formulated  a  theory  of  species- 
forming  by  sudden  considerable  variations,  namely,  muta- 
tions ;  in  1901  and  1903  appeared  the  two  volumes  of  de 
Vries's  "Die  Mutationstheorie/'  in  which  are  revealed  the 
results  of  long  years  of  careful  personal  observation,  in 
truly  Darwinian  manner,  directed  toward  the  testing  and 
better  grounding  of  this  mutationstheorie  of  species-origin. 
The  results  are :  out  of  many  plant  species  studied,  a  few 
show  at  certain  times  in  the  course  of  numerous  generations 
a  behaviour  in  accordance  with  the  demands  of  a  theory 
of  species-forming  by  sudden  definitive  modification;  that 
is,  species-forming  by  mutations.  The  mutations-theory 


DARWINISM   ATTACKED.  29 

thus  launched  is  offered  as  a  substitute  for  the  natural 
selection  theory  obviously  weakening  under  the  fire  of 
modern  scientific  criticism.  But  however  effective  de 
Vries's  facts  are  in  proving  the  possibility  of  the  occurrence 
of  other  variations  than  those  fortuitous  ones  occurring  in 
continuous  series  from  mean  to  opposite  extremes  which  Dar- 
win recognised  as  the  basis  of  species-forming,  and  however 
effective  they  are  in  proving  the  actual  production  of  three 
or  six  or  ten  species  by  mutation,  and  however  effective  in 
both  these  capacities  they  are  as  weapons  of  attack  on  the 
dominance  of  the  Darwinian  theory  of  species-making, 
how  really  inadequate  are  they  to  serve  as  the  basis  of  a 
great  all-answering  theory  explaining,  in  a  causo-mechanical 
way,  the  facts  of  descent,  or  even  the  primary  facts  of  gen- 
eral species-forming.  And  yet  the  first  American  book4 
(from  the  pen  of  one  of  America's  foremost  biologists)  to 
discuss  the  modern  phase  of  unrest  and  dissatisfaction  in 
evolutionary  matters,  practically  accepts  the  mutations- 
theory  as  a  substitute  for  the  selection  theory  of  species- 
forming.  It  cannot  be,  it  seems  to  me,  that  Professor 
Morgan  is  so  satisfied  with  the  mutations-theory,  that  he 
clutches  it  up,  hardly  definitely  formed  and  cooled,  from  the 
de  Vriesian  moulds,  but  that  he  is,  like  many  another  present- 
day  biologist,  so  profoundly  dissatisfied  with  the  natural 
selection  theory.  For  my  part  it  seems  better  to  go  back 
to  the  old  and  safe  Ignoramus  5  standpoint. 

But  I  have  been  led  to  anticipate  my  conclusions ;  let  us 
make  another  beginning  with  the  real  undertaking  of  this 
chapter  and  get  to  the  actual  specifications  of  "Darwinism 
Attacked."  We  shall  concentrate  the  attacks  and  attackers  in 
this  and  the  two  following  chapters ;  then  include  in  the  suc- 
ceeding two  the  defence  and  the  defenders,  and  in  the  next 
four  chapters  the  various  supporting  and  substitutionary 
theories  offered  by  the  friends  and  foes  of  Darwinism. 
Finally,  in  the  last  chapter  we  shall  set  out  what  we  can 


30  DARWINISM   TO-DAY. 

discover,  in  the  haze  of  the  smoke  of  battle,  of  the  actual 
present  state  of  the  besieged  and  besiegers. 

Distinctly  the  most  comprehensive,  the  fairest-minded 
review  of  gegen-itnd-fiir  Darwinisimis  in  recent  literature  is 
Plate's  extension  of  his  address,  "Uber  die  Bedeutung  des 
Darwin'schen  Selectionsprincips,"  made  in  Hamburg  be- 
fore the  Deutsche  Zoologische  Gesellschaft  in  1899.  To 
this  review,  as  published  in  1903  after  being  extended  and 
brought  up  to  date,  I  beg  to  acknowledge  a  special  indebted- 
ness in  my  present  attempt  to  get  together  the  more  im- 
portant criticism,  both  adverse  and  defensive,  of  Darwin. 
I  have,  however,  assiduously  sought  out  (with  the  help  of 
librarians  and  my  indefatigable  Leipzig  book-dealer  friend 
Bernh.  Liebisch),  and  perused  the  original  pourings-forth  of 
criticism  and  vilification  even  to  the  reading  of  some  matter 
written  by  certain  Roman  Catholic  priests  with  a  consider- 
able amateur  interest  in  natural  history  and  a  strong  pro- 
fessional interest  in  anti-Darwinism!  But  Plate  has  been 
a  guiding  hand  in  this  search  for  active  attacks  and  de- 
fence. 

The  natural  selection  theory  as  an  all-sufficient  explanation 
of  adaptation  and  species-forming  has  always  had  a  weak- 
ness at  its  base ;  it  depends  absolutely,  of  course,. 
_  Natural  selec-  on  ^he  pre-existence  of  variations,  but  it  itself 

tion  theory  based  ; 

on  variation,  has  no  influence  whatever  on  the  origin  or  con- 
trol of  these  variations  except  in  so  far  as  it  may 
determine  what  individuals  shall  be  permitted  to  give  birth 
to  other  individuals.  Now  one  of  the  chief  problems  in 
biology  is  exactly  that  of  the  origin,  the  causes,  and  the 
primary  control  of  these  congenital  variations.6  Three 
principal  explanations,  no  one  of  them  experimentally 
proved  or  even  fairly  tested  as  yet,  have  been  given  of  this 
actually  occurring  congenital  variation,  viz.,  (i)  that  there 
exists  in  the  germ-plasm  an  inherent  tendency  or  capacity 
to  vary  so  that  there  is  inevitable  variation  in  all  individuals 


DARWINISM   ATTACKED.  3* 

produced  from  germ-plasm,  this  variation  being  wholly- 
fortuitous  and  fluctuating  according  to  some  (the  belief  of 
Darwin  and  his  followers),  or,  according  to  others,  this 
variation  following  certain  fixed  or  determinate  lines  (de- 
terminate variation,  orthogenetic  variation,  etc.)  ;  (2)  that 
amphimixis,  *'.  e.,  bi-parental  parentage,  is  the  principal 
cause  of  variation,  it  seeming  logical  to  presume  that  indi- 
viduals produced  from  germ-cells  derived  from  the  fusion 
of  germ-plasm  coming  from  two  individuals  more  or  less 
unlike  would  differ  slightly  from  either  of  the  parental 
individuals;  and  (3)  that  congenital  variation  is  due  to  the 
influence  of  the  ever-varying  environment  of  the  germ-cell 
producing  individuals.  The  objections  to  any  one  of  these 
theories  may  be  very  pertinent,  as  when  one  says  regarding 
the  first  that  calling  a  thing  "inherent"  is  not  clearing  up  in 
any  degree  a  phenomenon  for  which  we  are  demanding  a 
causo-mechanical  explanation;  or  of  the  second  that  it  has 
been  proved  7  that  individuals  produced  parthenogenetically, 
that  is,  from  an  unmated  mother,  vary  and  in  some  cases 
vary  even  more  than  do  other  individuals  of  the  same  species 
produced  by  amphimixis ;  or  of  the  third  that  as  far  as  our 
study  of  the  actual  processes  and  mechanism  of  the  produc- 
tion of  germ-cells  and  of  embryos  has  gone,  we  have  found 
no  apparent  means  whereby  this  influence  of  the  ambient 
medium  can  be  successfully  impressed  on  the  germ-plasm. 
But  however  pertinent  the  objections  to  the  why  of  varia- 
tion may  be  they  do  not  in  any  way  invalidate  the  fact  that 
variations  do  continuously  and  inevitably  occur  in  all  indi- 
viduals, and  that  while  many  of  these  variations  are  recog- 
nisably  such  as  have  been  impressed  on  the  individual  during 
its  personal  development  as  immediate  results  of  varying 
temperature,  amount  or  kind  of  food,  degree  of  humidity, 
etc.,  to  which  it  may  be  exposed  in  its  young  life,  others 
seem  wholly  inexplicable  on  a  basis  of  varying  individual 
environment  and  are  certainly  due  to  some  antenatal  influ- 


32  DARWINISM   TO-DAY. 

ence  acting  on  the  germ-plasm  from  which  the  embryo  is 
derived. 

Now  the  natural  selection  theory,  in  its  Darwinian  and 

neo-Darwinian    form,    presupposes    fortuitously    occurring 

congenital    variations     of    practically    infinite 

Darwinian,  or    variety  in  all  parts  of  all  organisms.     Actual 

continuous,  varia- 
tion according  to  observation  shows  that  all  parts  of  all  organ- 

chanc7°f  isms  do  vary  and  that  they  vary  congenitally, 
that  is,  independently  of  any  immediate  in- 
fluence during  development  exercised  from  without  by 
environmental  conditions,  as  well  as  in  response  to  these 
environmental  influences,  and  finally  that  in  many  cases  this 
variation  is  fortuitous,  that  is,  that  it  occurs  according  to 
the  laws  8  of  chance.  The  industrious  statistical  study  of 
variations,  including  the  tabulation  of  the  variation  con- 
dition in  long  series  of  individuals  of  the  same  species  or 
race  and  the  mathematical  formulation  of  this  variation 
condition,  have  shown  that  in  many  specific  cases,  studied 
in  numerous  kinds  of  animal  and  plant  forms,  the  character 
of  the  variation  in  any  particular  character  may  be  truly 
represented  (with  close  approximation)  by  the  mathematical 
expression  and  curve  which  would  exactly  define  the  condi- 
tion in  which  the  variation  would  exist  if  it  actually  followed 
the  law  of  error.  It  is  these  continuous  series  of  slight 
variations,  these  variously  called  fluctuating,  individual,  or 
Darwinian  variations,  occurring  in  all  organisms  at  all  times 
and  often  following,  in  their  occurrence,  the  laws  of  chance, 
on  which  Darwin's  theory  of  species-forming  by  natural 
selection  is  based.  But  this  same  industrious  statistical 
and  quantitative  study  of  variation,  which  has  proved 
that  some  variations  do  occur  regularly,  fluctuating 
around  a  mean  or  mode,  has  shown,  as  well,  that  in 
many  cases  the  variations  distinctly  tend  to  heap  up 
on  one  side  or  the  other  of  the  mean,  that  is,  that  they 
tend  to  occur  along  certain  lines  or  toward  certain  direc- 


DARWINISM    ATTACKED.  33 

tions  rather  than  uniformly  out  in  all  directions.  Also  it 
is  true,  and  this  has  of  course  been  long  known,  that  by 
no  means  all  variations  are  so  slight  nor  in 
variation,1™  '  suc^  Perfectfy  gradatory  or  continuous  series 
as  is  true  of  the  gradatory  Darwinian  variations. 
"Sports"  have  been  known  to  breeders  of  plants  and  animals 
ever  since  plant  and  animal  breeding  began.  Bateson  has 
rilled  a  large  book  *  with  records  of  "discontinuous  varia- 
tions" in  animals ;  variations,  that  is,  of  large  size  and  not 
occurring  as  members  of  continuous  gradatory  series.  So 
that  biologists  are  acquainted  with  many  cases  of  variation 
that  seem  to  be  of  a  kind,  or  to  exhibit  a  tendency,  to  in- 
stitute special  directions  of  development,  and  thus  not  to  be 
of  the  simple,  non-initiating,  inert  character  of  the  fortuitous, 
slight,  fluctuating  variations,  among  which  natural  selection 
is  presumed  to  choose  those  that  are  to  become  the  be- 
ginnings of  new  lines  of  modification  and  descent.  Many 
biologists  believe  firmly  that  variations  occur  in  many 
special  cases,  if  not  in  most  cases,  only  along  certain  special 
lines.  Palaeontologists  believe,  practically  as  a  united  body, 
that  variation  has  followed  fixed  lines  through  the  ages; 
that  there  has  been  no  such  unrestricted  and  utterly  free  play 
of  variational  vagary  as  the  Darwinian  natural  selection 
theory  presupposes. 

Now  it  is  at  least  obvious  that  natural  selection  is  abso- 
lutely limited  in  its  work  to  the  material  furnished  by  varia- 
tion; so  that  if  variation  occurs  in  any  cases 
Determinate     onty  along  certain  determinate  lines  selection 

variation  as  a        can  fa  no  more  than   make  use   of  these   lines. 

species-forming  .      . 

factor.  Indeed  if  variation  can  occur  persistently  along 

determinate  lines  natural  selection's  function  in 
controlling  evolution  in  such  cases  is  limited  to  the  police 
power  of  restricting  or  inhibiting  further  development  along 
any  one  or  more  of  these  lines  which  are  of  a  disadvan- 
tageous character,  that  is,  a  character  which  handicaps  or 


34  DARWINISM   TO-DAY. 

destroys  the  efficiency  of  its  members  in  the  struggle  for  life. 
The  question  in  many  men's  mouths  to-day  is,  Why  may  not 
variation  be  the  actual  determinant  factor  in  species-forming, 
in  descent?  It  actually  is,  respond  many  biologists  and 
palaeontologists. 

Even  Darwin  believed  such  determinate  variation  to  occur, 
as  is  indicated  by  repeated  statements  in  the  "Origin  of 
Species."  In  chapter  iv  he  says  (to  refer  to  but  a  single 
one  of  these  admissions)  :  "It  should  not,  however,  be  over- 
looked that  certain  rather  strongly  marked  variations,  which 
no  one  would  rank  as  mere  individual  differences,  fre- 
quently recur  owing  to  a  similar  organisation  being  similarly 
acted  on — of  which  fact  numerous  instances  could  be  given 
with  our  domestic  productions.  In  such  cases,  if  the  vary- 
ing individual  did  not  actually  transmit  to  its  offspring  its 
newly  acquired  character,  it  would  undoubtedly  transmit  to 
them,  as  long  as  the  existing  conditions  remain  the  same, 
a  still  stronger  tendency  to  vary  in  the  same  manner.  There 
can  also  be  little  doubt  that  the  tendency  to  vary  in  the 
same  manner  has  often  been  so  strong  that  all  the  individuals 
of  the  same  species  have  been  similarly  modified  without  the 
aid  of  any  form  of  selection.  Or  only  a  third,  fifth,  or 
tenth  part  of  the  individuals  may  have  been  thus  affected,  of 
which  fact  several  instances  could  be  given.  Thus  Graba 
estimates  that  about  one-fifth  of  the  guillemots  in  the  Faroe 
Islands  consist  of  a  variety  so  well  marked,  that  it  was 
formerly  ranked  as  a  distinct  species  under  the  name  of 
Uria  lacrymans.  In  cases  of  this  kind,  if  the  variation  were 
of  a  beneficial  nature,  the  original  form  would  soon  be  sup- 
planted by  the  modified  form,  through  the  survival  of  the 
fittest." 

This  problem  of  the  existence  or  non-existence  of  deter- 
minate variation  is  taken  up  in  such  detail  in  connection  with 
the  explanation  and  discussion  of  various  auxiliary  or  alter- 
native theories  of  species-forming  in  later  chapters  of  this 


DARWINISM   ATTACKED.  35 

book  that  it  need  not  detain  us  now.    But  to  my  mind  it  is 

one  of  the  most  important  matters  in  connection  with  the 

whole   great   problem   of   descent,   that   is,   of 

Does  determi-  ° 

nate  variation  evolution.  It  is  the  basic  problem  of  evolu- 
tion, for  it  is  the  problem  of  beginnings. 
Selection,  isolation,  and  the  like  factors  are  conditions 
of  species-forming;  variation  is  a  prerequisite,  a  sine 
qua  non.  True  variation  must  have  its  causes,  and  these 
causes  are  to  be  determined  before  an  actual  causo-me- 
chanical  explanation  of  evolution  can  ever  be  found.  But 
the  determination  of  the  relation  of  variation  to  species- 
forming  is  certainly  the  first  step  now  necessary  in  our 
search  for  the  basic  factors,  the  real  first  causes  of  species 
change. 

But  even  in  those  cases  where  there  may  exist  unrestricted 

indeterminate  fluctuating  variation  in  continuous  series  ac- 

Whatdoes        cording  to  the  law  of  error,  what  is  it  that  this 

fluctuating  vari-  variation    really    offers    natural    selection    to 

ation  offer  selec- 

tion as  a  basis  for  WO  rk   on?     Remember   what   natural   selection 


species-forming?  js  .  the  saying  of  Qne  Qr  tefl  by  the  actual  kming. 

of  the  thousand  or  ten  thousand  because  in  the  struggle  for 
existence  the  variations  of  the  one  or  ten  are  of  sufficient 
advantage  to  have  a  life-or-death-determining  value.  Now 
between  any  two  successive  individuals  in  a  series  arranged 
on  a  basis  of  the  variations  in  any  one  character  of  any  one 
organ  or  function,  the  difference,  is  extremely  slight,  too 
slight,  one  is  certain,  to  be,  in  most  cases,  of  life  or  death 
value.  But  even  if  one's  conception  of  the  absolute  inten- 
sity of  the  rigour  of  the  personal  struggle  leads  to  a 
logical  conception  of  an  absolute  advantage  in  any  differ- 
ence, however  slight,  in  a  favourable  direction,  it  is  wholly 
possible  that  for  any  other  characteristic  equally  important 
in  the  struggle  the  two  individuals  may  be  in  exactly  reversed 
position,  the  one  possessing  the  infinitesimal  advantage  in 
strength  say,  possessing  an  infinitesimal  disadvantage  in 


36  DARWINISM   TO-DAY. 

sharpness  of  claw  or  in  agility.  What  of  the  chances  for 
such  a  necessary  coincidence  in  the  one  individual  of  favour- 
able variations  in  all  the  ways  necessary  to  create  a  real  life- 
or-death-determining  advantage?  The  law  of  probabilities 
answers  that  much  to  the  dismay  of  the  Darwinian.  But, 
again,  why  not  compare  the  chances  in  the  struggle  of  two 
individuals  not  standing  side  by  side  in  a  variational  series, 
but  at  two  extremes  of  the  range ;  the  difference  here  can  be 
considerable,  can  be  of  positive  advantage  or  disadvantage. 
Yes,  but  again  comes  the  necessity  of  presupposing  a  coin- 
cidence of  other  advantages  or  at  least  of  no  coincidence  of 
balancing  advantages  and  disadvantages.  But  even  more 
fatal  is  the  condition  that  if  an  extreme  variation  in  some  one 
character  could  be  of  a  life-preserving  advantage,  yet  by  the 
law  of  probabilities  (and  by  the  tale  of  actual  observation) 
those  individuals  standing  at  the  extremes  of  the  range  of 
variation  are  very,  very  few  compared  with  those  standing 
nearer  the  mean,  or  mode,  of  the  series,  and  there  would 
be  almost  a  certainty  of  such  an  extreme-charactered  sur- 
vivor not  finding  a  similar  form  with  which  to  mate  and  thus 
insure  perpetuation  of  the  advantage,  the  mating  of  the 
individuals  admittedly  not  depending  on  any  necessary 
similarity  in  variation  (unless  the  varying  characteristics 
happen  to  be  actually  concerned  with  the  mating  act:  see 
later  discussion  of  biological  isolation,  chapter  ix).  Con- 
siderable variations,  the  only  ones  of  apparent  worth  in  a 
life-and-death  struggle,  are  in  such  meagre  disproportion 
to  the  less  considerable  that  they  are  inevitably  swamped, 
extinguished,  in  miscellaneous  cross-mating. 

Let  us  consider  a  little  more  in  detail  each  of  the  various 

objections  mentioned  in  the  last  few  pages.    Only  the  student 

of  systematic  (classificatory)  zoology  or  botany 

Insignificance  *  /.  .,. 

of  fluctuating  can  realise  how  slight  and  insignificant  are  the 
variations,  various  miscellaneous  individual  variations 
which  make  up  that  basis  of  ever-present,  myriad-faced, 


DARWINISM   ATTACKED.  37 

fortuitous,  fluctuating  variability  on  which  the  whole  great 
structure  of  the  selection  theory  is  based.  Yet  any  one's 
common  sense  and  his  intuitive  comprehension  of  what 
life-and-death  value  is  in  an  animal's  battle  with  another, 
with  foreign  enemies,  or  with  inclement  Nature,  make 
this  objection  of  "no  handle  for  natural  selection  in  mis- 
cellaneous slight  variation"  thoroughly  appreciable.  Polar 
bears  are  probably  descended  from  brown;  and  their  white 
fur  coat  is  probably  an  advantageous  adaptation  in  their 
life  in  the  Arctic.  But  did  the  fortuitous  appearance  in  his. 
coat  of  a  spot  of  white  hairs  as  large  as  a  dollar  or  a  pancake 
give  some  ancient  brown  bear  such  an  advantage  in  the 
struggle  for  existence  as  to  make  him  or  her  the  fore^ 
runner  of  a  new  and  better-adapted  sort  of  bear  ?  ifThe 
giraffe's  long  neck  is  very  much  worth  while  to  it;  it  gets, 
leaves  from  the  higher  branches  unattainable  by  the  short- 
necked  animals  who  find,  food  in  the  same  range.  But  did  a 
millimetre  or  even  an  inch  of  extra  neck  appearing  as 
individual  variation  in  an  ancestral  short-necked  giraffe 
kind  give  natural  selection  a  handle  with  which  to  grind  out 
a  new  species?  The  consideration  of  the  usefulness  of 
slight  variations  too  often  leads  to  an  argument  for  their 
usefulness  on  the  same  grounds  as  sustain  the  belief  that 
the  hound  will  never  catch  the  hare  which  goes  one-half  as 
fast  as  the  dog.  For  each  time  the  hound  covers  the  given 
stretch  that  lies  between  him  and  the  hare  at  any  given 
moment  the  hare  will  be  just  one-half  that  distance  in 
advance — and  though  the  distance  will  get  ever  shorter  and 
shorter  the  hare  will  ever  be  one-half  the  last  distance  ahead. 
So  say  the  sophists.  As  a  matter  of  fact  the  hound  gets  the 
hare. 

Spencer's  example  of  the  femur  of  the  whale  is  a  striking 
illustration  of  the  reality  of  the  absurdity  connected  with 
the  argument  of  change  on  .a  basis  of  the  selection  of  in- 
finitesimal differences.  The  femur  of  the  whale,  says 


38  DARWINISM   TO-DAY. 

Spencer,  is  evidently  the  atrophied  rudiment  of  a  bone  once 
much  larger.     It  weighs  now  about  one  ounce,  less  than  a 

millionth   of   the   weight   of   the   whole   body. 
Spencer's  ex-  J 

ample  of  the  Let  us  suppose  that  when  it  weighed  two 
^a"ofthe  ounces  an  individual  had  a  femur  which  by 
variational  chance  weighed  but  one  ounce. 
What  advantage  over  other  whales  would  the  difference  give 
it?  What  fraction  of  the  daily  nourishment  would  this  ad- 
vantageous variation  permit  the  fortunate  whale  to  add  to  its 
stored  fat  instead  of  spending  it  on  an  extra  ounce  of  useless 
femur?  Who  would  dare  claim  that  this  variation  would 
aid  in  success  in  the  struggle  for  existence  ?  And  yet  this  is 
the  argument  for  the  reduction  of  useless  organs  through 
the  influence  of  natural  selection.  Roux  and  Weismann, 
realising  the  absurdity  of  the  argument,  have  put  forward 
two  theories,  one  called  the  "battle  of  the  parts"  and  the 
other  the  "theory  of  germinal  selection"  to  aid  the  selection 
theory  to  explain  the  degeneration  and  reduction  of  organs. 
The  reader  will  find  these  theories  explained  in  chapter  viii. 
Every  student  of  systematic  zoology  or  botany  has  a  keen 
realisation,  too,  of  the  fact  that  a  majority  of  the  distinguish- 
ing characters  which  he  recognises  in  the  vari- 
Many  species  Ous  species  and  genera  that  come  under  his 

•characters  of  no  ..  .  .. 

utility,  eye  are  of  a  sort  that  reveal  to  him  no  trace  of 

particular  utility  or  advantage.  Indeed  he  can 
go  farther  and  express,  to  himself  at  least,  his  conviction 
that  many  of  these  slight  but  constant  specific  differences  10 
can  actually  have  no  special  advantageousness  about  them. 
One's  experience  as  an  observer  of  nature  and  one's  common 
sense  combine  to  protest  against  that  easy  and  sweeping 
answer  of  the  Darwinians :  "shall  'poor  blind  man'  say  what 
characteristic,  however  slight  and  insignificant,  is  or  is  not 
of  advantage  in  the  great  complex  of  nature?"  As  the 
-whole  question  after  all  resolves  itself  into  one  for  which 
""poor  blind  man"  is  attempting  to  find  an  answer  satisfying 


DARWINISM   ATTACKED.  39 

to  his  own  understanding,  however  short  of  perfection  and 
omniscience  that  is,  he  is  bound  to  answer  the  subsidiary 
problems  such  as  usefulness  or  non-usefulness  on  a  basis  of 
his  own  seeing  and  understanding  capacity.  As  a  matter 
of  fact  the  indifference  of  many  specific  characteristics  of 
organisms  is  not  denied  by  selectionists.  Romanes  1X  was 
perhaps  the  first  representative  Darwinian,  after  Darwin 
himself,  to  admit  this.  But  many  biologists  say,  further,  on 
a,  basis  of  their  experience  as  observers,  that  these  very 
indifferent,  meaningless  (as  far  as  utility  goes)  mor- 
phological characteristics  and  differences  are  much  more 
constant  in  their  character  than  the  obviously  adaptive,  i.  e., 
useful  ones.  However,  as  pointed  out  first  by  Niigeli,  accord- 
ing to  the  selection  theory  the  characteristics  of  organisms 
should  be  just  in  that  degree  the  more  constant,  the  more 
useful  they  are.  Hence  there  is  here  a  serious  discrepancy 
between  theory  and  fact.  Darwin  himself  felt  the  force  of 
this  objection  and  met  it  in  a  manner  not  at  all  acceptable 
to  the  ultra-Darwinians,  that  is  the  strict  selectionists  of 
post-Darwinian  times.  He  admitted  that  these  trivial,  ap- 
parently non-useful,  but  constant  specific  characters  could 
not  be  explained  by  natural  selection,  and  must  be  due  to  a 
fixation  in  the  species  of  these  characters  at  one  time  or 
another  through  the  nature  of  the  organism  and  the  influ- 
ence of  extrinsic  influences ;  a  true  Lamarckian  or  at  least 
anti-Weismannian  *  explanation. 

This  objection  to  the  selection  theory  based  on  the  ad- 

*  Students  and  readers  who  have  not  read  Darwin  recently,  or 
in  the  light  of  the  controversy  between  the  neo-Darwinians  and  the 
neo-Lamarckians,  that  is,  between  those  who  disbelieve  and  those 
who  believe  in  the  inheritance  of  acquired  characters,  will  be  sur- 
prised to  note  on  a  careful  re-reading  of  the  "Origin  of  Species," 
with  this  post-Darwinian  sharp  distinction  in  mind,  how  often  Dar- 
win calls  on  the  Lamarckian  factors  to  help  his  species-forming 
theories  out  of  tight  places.  Morgan  in  his  "Evolution  and  Adap- 
tation" points  out  many  cases  of  this. 


40  DARWINISM   TO-DAY. 

mitted  existence  of  indifferent  species  characters  is  well  stated 
,  by  Conn  12  as  follows :  "But  how  is  it  with  char- 

mentoftheob-  acters  that  have  no  utility?  It  is,  of  course,  a 
to  L?aSote°~  £reat  achievement  to  be  able  to  point  out  the 
trivial  charac-  method  by  which  adaptations  have  been  pro- 
duced, but  if  animals  have  some  characters  that 
are  not  useful,  natural  selection  does  not  explain  them. 
Natural  selection  can  develop  useful  organs  only.  The  real 
problem  which  our  naturalists  are  trying  to  solve  is  not  the 
origin  of  adaptations  simply  but  the  origin  of  species  also. 
Now  while  many  of  the  characters  and  organs  of  animals 
and  plants  are  of  utility  to  the  individual  there  are  others 
that  appear  to  be  useless.  As  animals  and  plants  are 
studied,  it  is  found  that  the  different  species  differ  from 
each  other  by  certain  definite  characters.  These  distinctive 
peculiarities  that  distinguish  species  are  called  'specific 
characters,'  and  this  term  will  be  hereafter  used  in  this 
sense.  The  explanation  of  the  origin  of  species  must  then 
account  for  the  origin  of  specific  characters.  Now  specific 
characters  are  frequently  trivial  in  nature.  This  was  long 
ago  recognised  by  Darwin,  who  saw  that  the  characters  by 
which  species  are  distinguished  are  frequently  so  trivial  as  to 
be  apparently  useless.  If,  however,  we  are  to  explain  the 
origin  of  species  we  must  find  an  explanation  of  these  trivial 
characters  as  well  as  the  more  important  ones.  If  these 
trivial  characters  are  of  ;i«  use  to  their  possessors,  then 
manifestly  the  principle  of  the  survival  of  the  fittest  does 
.not  account  for  them.  The  fact  that  species  are  so  com- 
monly separated  by  characters  that  seem  to  be  absolutely 
useless  has  led  some  of  our  keenest  naturalists  to  insist  that 
the  survival  of  the  fittest  does  not  explain  the  origin  of 
species,  but  explains  only  the  origin  of  adaptations.  At  all 
events,  it  is  clear  that  the  problem  of  the  utility  of  specific 
characters  is  a  very  fundamental  one  to  the  discussion  of  the 
principle  of  survival. 


DARWINISM   ATTACKED.  4* 

"We  here  come  to  the  first  parting  of  the  ways  between 
scientists  of  different  schools.  On  the  one  hand  we  find  those 
who  are  so  thoroughly  convinced  of  the  universality  of  the 
principle  of  natural  selection  that  they  insist  that  all  specific 
characters  are  useful,  however  useless  they  may  seem.  It 
is  beyond  question  that  they  are  led  to  this  belief  in  the 
utility  of  all  characters,  not  from  observation,  but  simply 
from  their  belief  in  the  sufficiency  of  the  law  of  natural 
selection.  They  tell  us  that  we  know  too  little  of  the  actual 
life  of  organisms  in  nature  to  enable  us  to  say  that  any- 
given  character  is  not  of  use ;  and  to  make  a  claim  that  any- 
thing, no  matter  how  trivial,  is  useless,  is  simply  to  confess 
ignorance.  We  must  acknowledge  that  many  seemingly 
useless  organs  have  been  found  to  have  utility  as  soon  as  the 
life  habits  of  animals  are  better  understood.  Certainly, 
utility  has  been  found  more  universal  than  was  believed  to 
be  possible  a  quarter  of  a  century  ago.  The  followers  of 
Darwin  have  given  very  much  attention  to  this  matter. 
They  have  pointed  out  many  lines  of  utility  hitherto  not 
dreamed  of.  They  have  considered  great  multitudes  of 
cases  of  seemingly  useless  characters,  and  by  a  little  imagina- 
tion have  suggested  some  use  to  which  they  may  be  adapted. 
If  one  reads  the  recent  works  of  Wallace,  the  most  promi- 
nent advocate  of  this  position,  he  will  not  fail  to  be  im- 
pressed with  the  fact  that  utility  is  much  more  widely 
applicable  as  an  explanation  of  seemingly  trivial  characters 
than  might  have  been  thought  possible.  The  position  held 
by  this  writer  is,  that  inasmuch  as  the  law  of  natural 
selection  is  a  universal  force  which  all  admit,  while  all  other 
forces  of  evolution  are  yet  in  dispute,  and  inasmuch  as  many 
seemingly  useless  organs  have  been  shown  to  be  of  use,  it  is 
perfectly  legitimate  to  claim  that  when  we  come  to  under- 
stand them,  we  shall  find  that  all  characters  are  of  value,  and 
that  the  principle  of  survival  of  the  fittest  has  been  concerned 
in  the  development  of  them  all.  If  this  is  true,  the  survival 


42  DARWINISM   TO-DAY. 

of  the  fittest  explains  the  origin  of  species  as  well  as  the 
origin  of  adaptations,  since  all  specific  characters  are  really 
adaptations. 

"But  on  the  other  hand,  many  naturalists  think  that  there 
are  specific  characters  for  which  we  cannot  only  see  no 
utility,  but  which  are  demonstrably  of  no  use.  A  few  illus- 
trations will  serve  to  make  the  matter  clearer.  Certain  in- 
sects are  distinguished  from  each  other  in  accordance  with 
whether  they  possess  one  or  two  bristles  on  the  head.  Here 
is  a  character  which  appears  to  be  constant,  and  which  must 
therefore  be  explained  by  any  complete  theory  of  the  origin 
of  species.  Can  we  imagine  that  the  question  of  whether 
the  animal  has  one  or  two  hairs  should  ever  have  been  of 
selective  value?  But  if  developed  by  natural  selection,  this 
character  must  at  some  time  have  been  a  matter  of  life  and 
death.  Again  among  snails,  the  shells  commonly  coil  in 
the  same  direction  in  the  same  species,  this  fact  making  the 
direction  of  the  coiling  of  the  shell  a  specific  character.  But 
clearly  this  is  not  a  matter  of  selective  value,  since  living 
among  the  rest  of  the  individuals  will  frequently  be  found 
some  with  their  shells  coiled  in  the  opposite  direction. 
Again,  horses  have  small  horny  callosities  on  their  feet.  No 
one  has  suggested  any  possible  use  for  them,  but  neverthe- 
less they  are  present  on  the  feet  of  all  the  species  of  the  horse 
family.  But  the  most  curious  fact  is  that  while  the  horse  has 
them  on  all  four  feet,  the  ass  has  them  on  only  two.  Now, 
upon  the  principle  that  utility  is  universal,  it  would  be  neces- 
sary to  claim,  not  only  that  the  presence  of  four  callosities 
has  been  a  matter  of  selective  value  in  the  horse,  an  ex- 
tremely difficult  thing  to  believe,  but  also  that  the  presence 
of  only  two  instead  of  four  has  been  of  selective  value  in  the 
ass.  This  position  approaches  absurdity.  Again,  there  are 
molluscs  characterised  by  special  markings  of  the  shell, 
which  markings  are  constant  enough  to  be  specific  char- 
acters, and  must,  of  course,  be  included  in  any  explanation 


DARWINISM   ATTACKED.  43 

of  the  origin  of  species.  But  these  marks  are  demonstrably 
of  no  use,  since  they  are  entirely  covered  by  the  epidermis 
of  the  animal  when  alive,  and  absolutely  invisible.  Again, 
some  birds  have  slight  differences  in  colour  markings  which 
separate  species.  Now  these  differences  may  perhaps  be  re- 
garded as  of  use  as  protective  or  as  recognition  marks. 
But  in  some  cases  the  colour  markings  are  entirely  con- 
cealed by  other  feathers  and,  being  invisible,  can  be  of  no 
possible  utility.  It  is  hardly  possible  for  one,  unless  he  has 
decided  previously  to  accept  the  all-sufficiency  of  natural 
selection,  to  believe  that  there  can  be  any  utility  in  the  very 
slight  differences  in  the  shape  of  leaves  of  plants,  in  the  micro- 
scopic markings  of  the  hairs  of  different  species  of  mammals, 
the  exact  numbers  of  the  feathers  in  the  tails  of  birds,  the 
peculiar  distribution  of  the  veins  in  the  wings  of  a  butter- 
fly, the  microscopic  markings  in  the  scales  on  its  wings,  or 
a  host  of  other  similar  trivial  characters.  When  it  is  re- 
membered that  the  selection  principle  would  force  us  to 
insist  that  all  of  these  characters  are  of  value  sufficient  to 
protect  their  possessors  at  the  expense  of  other  individuals 
not  possessing  them,  it  is  evident  that  the  burden  thrown 
upon  the  principle  of  survival  becomes  very  great.  When 
finally  we  come  to  characters  of  specific  nature  connected 
with  colour  markings  which  are  invisible  when  the  animal 
is  alive,  there  is  apparently  no  resource  left  except  to  con- 
clude that  the  principle  of  survival  because  of  utility  does 
not  account  for  everything." 

It  is  indeed  the  general  recognition  by  naturalists  of  the 
fact  of  the  triviality  or  indifference  of  a  majority  of  specific 
characters  that  has  led  to  the  recent  renewal  of  the  import- 
ance of  isolation  theories,  particularly  of  geographical 
isolation.  The  rehabilitation  of  Moritz  Wagner's  theory  of 
species-forming  by  migration  and  isolation  is  a  conspicuous 
feature  in  present-day  evolution  discussion.  The  way  in 
which  isolation  comes  to  the  aid  of  selection,  or  even  sup- 


44  DARWINISM   TO-DAY. 

plants  it  in  the  minds  of  some,  in  species-forming  is  pointed 
out  in  chapter  ix,  to  which  the  interested  reader  may 
refer. 

But  in  those  cases  where  the   differences  or  variation 

among  individuals  may  be  or  obviously  are  of  the  character 

The  swamping  of  useful  ones,  and  where  by  comparing  ex- 

or  extinguishing  tremes    of    this    variation    the    life-and-death- 
of  favourable  va- 
riations by  inter-  determining    worth    of    this    utility    might    be 

lngl  conceded,   still  what  chance   is  there   for   the 

perpetuation  of  this  advantage?  Nageli  long  ago  pointed 
out  that  the  extreme  variations,  that  is,  the  rare  variations, 
would  in  almost  every  case  be  inevitably  extinguished  by 
interbreeding.  If  a  certain  considerable  variation  occurred 
in  one  individual  of  a  hundred  born,  in  20,000  individuals  of 
the  species  200  would  have  this  worth-while  variation. 
Now  if  the  chances  of  mating  are  the  same  for  all  there 
would  be  9,801  parings  of  individuals  not  showing  the 
variations,  198  pairings  between  a  varying  individual  and  a 
non-varying  one,  and  a  single  mating  between  two  indi- 
viduals both  preserving  the  considerable  variation.  In  fact 
every  rare  variation  will,  as  Delage  says,  be  immediately 
effaced  by  the  dilution  of  the  blood  of  the  varying  individual 
by  that  of  the  great  mass  of  individuals  not  possessed  of  the 
particular  variation.  This  inevitable  swamping  of  the  ad- 
vantageous variations  of  individuals  has  long  ago  led  to  the 
practical  giving  up  by  Darwinians  of  any  claims  to  species- 
forming  or  evolution  on  the  basis  of  extreme  or  rare  varia- 
tions and  to  the  restriction  of  the  selecting  influence  to 
masses.  The  species  must  be  changed  through  the  selection 
of  it  as  a  mass  or  unit  rather  than  through  the  selection  of 
special  scattered  individuals  of  it. 

But  for  the  selection  of  masses  of  individuals  sufficiently 
considerable  to  avoid  the  extinguishing  of  the  fortunate 
variations  by  interbreeding,  and  to  insure  a  repetition  of 
the  advantage  and  an  opportunity  for  its  fostering  and 


DARWINISM   ATTACKED.  45 

increase,  there  is  necessary  an  extraordinary  coincidence  in 

the  appearance  of  the  needed  variations  in  many  forms  at 

The  needed  co-  tne  right  time.    That  is,  a  theory  based  on  chance 

incident  occur-     or  accidental  phenomena  demands  after  all  the 

rence  of  several  . 

variations  at  one  assumption   of  the  occurrence   of  phenomena 
tlme>  of  the   right  kind   at  the   right  moment,   and 

the  persistence  of  such  occurrences  through  a  definite 
time-period.  This  is  too  much  to  assume,  too  much  to  ask 
even  of  those  of  the  true  faith,  say  the  antagonists  1S  i4  of 
the  selection  theory.  Kronig  15  makes  sport  of  the  selection 
doctrine  by  having  his  rather  frivolous  character,  Sabiich- 
winski,  undertake  to  have  made,  by  a  foolish  clown,  various 
trifling  changes  in  all  kinds  of  industrial  products  with  the 
expectation  of  bringing  them  into  the  market.  He  is  con- 
vinced that  he  will  win  a  fortune  by  this,  for  he  says  to 
himself  that  the  struggle  for  supremacy  must  work  out  the 
same  in  the  industries  as  in  nature,  and  in  his  case  with  the 
added  advantage  that  the  changes  effected  by  even  the  most 
slender-witted  boor  must  result  better  than  those  which  are 
the  outcome  of  perfectly  blind  chance.  Indeed,  from  the 
very  heart  of  the  neo-Darwinian  ranks  come  signs  of  dis- 
may when  this  objection  is  faced.  Weismann,  leader  of  the 
ultra-selectionists,  practically  concedes  the  irrefutability  of 
this  objection  to  the  Allinacht  of  selection  when  he  intro- 
duces a  statement  of  his  latest  theory,  that  of  Germinal 
Selection,  by  saying:16  "Knowing  this  factor  [that  of  germi- 
nal selection]  we  remove,  it  seems  to  me,  the 

Weismann's  .    ,  -11 

admission  of  the   patent  contradiction  of  the  assumption  that  the 


§"eneral  fitness  of  organisms  or  the  adaptations 
necessary  to  their  existence  are  produced  by 
accidental  variations  —  a  contradiction  which  formed  a  seri- 
ous stumbling-block  to  the  theory  of  selection."  And  the 
formulation  of  the  theory  of  germinal  selection  is  of  itself 
a  practical  confession  on  the  part  of  the  foremost  neo- 
Darwinian  of  the  inability  of  natural  selection  to  explain 


46  DARWINISM   TO-DAY. 

species-forming  without  calling  to  its  aid  some  effective 
factor  to  control  in  its  beginnings  the  variation  essential 
as  the  basis  of  the  selective  action. 

Pfeffer  17  and  Wolff  1B  have  been  particularly  keen  and 
severe  in  their  criticism  of  the  selection  theory  on  the  basis 
of  this  objection.  And  Morgan  19  in  this  country  has  also 
made  effective  use  of  this  weapon  in  his  destructive  con- 
sideration of  the  Darwinian  theories. 

There  is  an  additional  point  about  this  difficulty  of  the 

necessity  for  a  certain  regularity  or  reliability  of  variation 

.in  order  to  make  a  beginning  basis  for  the  action 

pi6C6ssitty  lor 

coincident  ap-      of  selection.     It  is  this.     Close  scrutiny  reveals 
the  necessity  often  of  the  occurrence  of  several 


make  a  certain  coincident  variations  in  order  to  make  any  one 
characteristic  positively  advantageous.  What 
advantage  in  the  way  of  increased  speed  is  a  slight  added 
length  of  leg  without  a  simultaneously  added  strength  of 
musculation  ;  or  an  increase  in  size  of  antlers  without  a 
simultaneous  increase  in  strength  of  neck  muscles  to  sup- 
port and  manipulate  the  heavier  head?  What  faint  prob- 
ability of  the  occurrence  coincidently  of  the  necessary  varia- 
tions (if  determined  only  by  chance,  that  is,  the  law  of  prob- 
ability) to  produce  a  gradual  perfecting  of  so  complex 
a  structure  as  the  vertebrate  eye?  Or,  more,  how  incon- 
ceivable the  coincidences,  if  variation  is  purely  fortuitous, 
necessary  to  the  simultaneous  development  of  two  exactly 
similar  eyes  :  two  eyes  so  intimately  associated  physio- 
logically that  normal  sight  is  a  function  of  both  these 
separated  organs  working  perfectly  together.  Is  variation 
to  be  assumed  to  be  governed  by  some  law  of  bilateral 
symmetry  ?  But  I  have  shown  for  many  cases  20  that  in  such 
perfectly  and  fundamentally  bilaterally  symmetrical  animals 
as  insects  neither  the  usual  Darwinian  fluctuating  variation 
nor  the  rarer  discontinuous  or  sport  variation  is  governed 
at  all  by  such  a  law.  In  fact  the  independence  of  the  varia- 


DARWINISM   ATTACKED.  47 

tion  phenomena  in  right  and  left  members  of  bilaterally 
arranged  pairs  of  organs  as  wings,  antennae,  legs,  etc.,  is  a 
noticeable  fact.  This  denial  of  the  capacity  of  the  selection 
of  fortuitous  slight  variations  to  account  for  coadaptation 
and  for  the  continuous  perfecting  of  complex  organs  has 
been  stated  as  follows  :  "It  is  highly  improbable  that  for  the 
steady  perfecting  of  an  organ,  the  variations  needed  by 
selection  will  always  appear  just  at  the  right  time."  Or  in 
more  expanded  form  :  "It  is  highly  improbable  that  during 
the  modification  of  a  complex  organ  such  as  a  whole  body 
part,  or  during  the  gradual  perfecting  of  an  adaptive  modi- 
fication, the  numerous  necessary  variations  will  appear  suc- 
cessively in  such  series  that  a  harmonious  combination  of 
the  single  variations  will  be  possible."  The  objection  cer- 
tainly needs  no  elaboration.  The  Darwinian  variations  ap- 
pear in  all  directions  at  all  times  in  slight  degrees  with  no- 
determinate  direction  nor  correlation.  Selection  is  to  find 
in  these  variations  its  only  material  with  which  to  build  up 
to  wonderful  complexity  and  perfection  of  coadaptation 
and  correlation  of  parts  21  on  a  basis  of  constant  advantage, 
such  an  intricate  but  harmoniously  adjusted  compound  organ 
as  the  human  eye,  in  which  the  failure  or  imperfectness  of  a 
single  minute  part  can  at  any  time,  during  the  course  of 
development,  rob  the  whole  of  any  advantage  whatever  to 
the  organism  possessing  it. 

Wolff  '2    enlarges   on    the    difficulty   of   explaining   any 
identical  structures  of  the  animal  body  which  appear  in  one 


Difficulty  of  tne  same  organism  to  the  number  of  two 

explaining  re-     or  more.    "It  cannot  be  explained,"  he  says,  "by 

peated  identical         ,     ,-         ,  ,,  •  * 

structures  by  selection,  how  the  carnivores,  for  example,  can 
selection.  have  developed  through  fortuitous  yet  always 

similar  variations,  two  such  structures  agreeing  in  all  de- 
tails as  the  back  teeth,  which  have  developed  in  course  of 
time  from  small  skin  teeth.  That  a  tooth  can  develop  into 
such  an  admirable  biting  organ  through  chance  variation  may 


48  DARWINISM   TO-DAY. 

be  explicable  by  selection,  because  we  are  accustomed  to 
postulate  thoroughly  fortuitous  and  all-inclusive  variation; 
but  that  the  tooth  standing  next  to  it  shall  have  varied  al- 
ways in  exactly  the  same  way  so  that  the  result  of  its  de- 
velopment shall  make  it  identical  with  the  other  one,  is 
inexplicable  by  selection  on  a  basis  of  fortuitous  variation, 
but  rather  indicates  that  the  change  of  form  is  ruled  by  law 
which  we  do  not  know.  The  attempt  to  discover  it  is  the 
most  imperative  task  for  biologists  to  undertake." 

Wolff  28  follows  this  argument  farther  by  discussing  other 

particular  examples,  but  they  are  all  of  the  type  of  the  one 

Spencer's  pic-    Just  set  out-     Spencer  pictures  the  situation  of 

tnre  of  the  inu-    the  herbivorous  animals   in   a   country   of   in- 

tility  of  advan- 

tage  in  a  single  clement  climate  and  populated  by  numerous 
carnivores.  Now  those  herbivores  which  have 
the  finest  hearing  will  be  soonest  aware  of  the  approach  of 
the  tiger,  but  those  with  keenest  sight  or  most  perfect  sense 
.of  smell  will  also  perceive,  as  soon,  that  it  is  time  to  flee.  But 
what  advantage  over  others  will  the  first  start  in  flight  give 
them?  Others  less  delicately  endowed  with  sense  organs 
but  swifter  of  foot  will,  although  starting  a  little  later,  have 
as  good  a  chance  to  escape  because  of  their  more  rapid  run- 
ning. Later  may  come  snow  and  terrible  cold.  Those  in- 
•dividuals  best  endowed  with  sense-organs  or  swiftest  of  foot 
will  not  necessarily  be  the  most  enduring  or  the  best 
equipped  with  instincts  to  find  shelter.  The  climate  may 
decimate  those  which  selection  on  the  basis  of  special  senses 
or  speed  has  saved.  But  after  the  cold  may  come  the  sum- 
mer drought.  Those  most  heavily  furred  or  warmest- 
blooded  which  have  successfully  endured  the  low  temperature 
and  snow  and  ice  of  winter  should  be  the  first  to  suffer  from 
the  attacks  of  sun  and  drought  and  lack  of  food  in  the 
summer.  Thus  no  individual  has,  because  of  advantage  in 
any  one  character,  any  real  and  complete  superiority  which 
guarantees  it  success  in  all  the  phases  of  the  struggle  for 


ACKED.  49 


existence:  the  advantages  are  scattered  and  compensated 
by  disadvantages.24 

In  connection  with  the  objection  stated  in  the  preceding 

paragraphs  is  that  specially  pressed  by  Wolff,  although  long 

Numerous  use-  a&°  strongly  stated  by  Mivart,25  and  one  that 

fal  characteris-    has  long  appealed  strongly  to  me  particularly  in 

tics  useful  only  -      ,  ,*-..  ,. 

in  highly  per-  connection  with  the  study  of  the  utility  of 
fected  state,  colour  and  pattern  among  insects.  This  ob- 
jection is,  that  numerous  useful  characteristics  or  adapta- 
tions of  organisms  are  useful  only  in  a  highly  perfected 
state,  often  involving  a  complex  and  considerable  structural 
development  of  old  (then  much  modified)  or  quite  new  parts, 
and  hence  could  not  have  arisen  by  gradual  modification  by 
the  selection  of  slight  variations.  Darwin  himself  says  that 
if  a  single  complex  organ  can  be  referred  to  whose  full  de- 
velopment cannot  possibly  be  explained  through  numerous 
small  successive  modifications,  then  his  theory  must  indubi- 
tably fall.  For  example,  the  electric  organ  of  the  torpedoes, 
the  brood-sacks  or  cells  on  the  back  of  Pipa  dorsigera,  the 
chameleon's  tongue,  and  many  other  organs  can  be  recalled 
which  could  not  possibly  exercise  their  particular  advanta- 
geous function  in  an  undeveloped  and  beginning  state.  In 
my  own  eyes  has  for  long  stood  the  familiar  case  of  the 
mimicry  of  our  common  American  monarch  butterfly, 
Mimicr  of  dnosia  plexippus,  by  the  viceroy  butterfly, 
Anosia  by  Basilarckia  archippus.  The  viceroy  belongs  to  a 
group  of  species  in  which  the  prevailing  (almost 
certainly  the  ancestral)  colour  and  pattern  are  white  and 
black  (or  iridescent  purplish  and  bluish)  arranged  as  a  broad 
white  continuous  transversal  bar  across  both  fore  and  hind 
wings,  on  a  black  (to  purplish)  ground.  The  colour  and 
pattern  of  Anosia  are  radically  different;  brick-red  ground, 
black  longitudinal  lines  following  the  veins  and  small  white 
spots  in  an  irregular  black  submarginal  band.  Examine  the 
viceroy  butterfly.  You  find  no  suggestion  of  typical  Basi- 


50  DARWINISM   TO-DAY. 

larchia  type  of  colour  and  pattern;  on  the  contrary,  you 
find  an  extraordinarily  faithful  imitation  (duplication)  of 
Anosia' s  colour  and  pattern.  Only  in  a  narrow  black  trans- 
versal streak  across  the  outer  disc  of  each  hind  wing  is  there 
any  divergence  in  the  viceroy  from  the  Anosia  pattern. 
Now  Anosia  is  distasteful  to  birds ;  after  a  few  experiments 
with  Anosia  a  bird  recognising  this  ill-tasting  morsel  in  its 
conspicuous  red-brown  livery  leaves  the  monarchs  alone.  Not 
only  monarchs,  however,  but  also  viceroys,  which  are  to  all 
external  seeming  only  slightly  smaller  monarchs.  The  viceroy 
is,  however,  not  distasteful;  it  would  be  a  welcome  bonne 
bouche  to  any  bird  that  could  distinguish  it.  But  thanks  to 
its  perfectly  mimicking  colour-pattern  it  wings  its  deceitful 
way  unmolested.  There  is  huge  usefulness  here,  and  selec- 
tion can  well  be  the  steadfast  maintainer  of  the  viceroy's 
dissimulation.  But  of  what  avail  for  this  purpose  of  deceit 
was  the  first  tiny  tinge  or  fleck  of  red-brown  on  the  staring 
black  and  white  wings  of  the  ancestral  viceroy?  How  can 
one  possibly  conceive  of  an  attainment  of  this  identity  of 
pattern  between  mimicker  and  mimicked  by  selection  on  a 
basis  of  life-or-death-determining  advantage  of  slight  chance 
appearances  of  brown  or  reddish  flecks  or  tinges  in  suc- 
cessive viceroys?  Not  until  practically  full  development  of 
the  mimicry  pattern  existed  can  this  pattern  have  worked  its 
advantage.  It  is,  indeed,  a  different  matter  with  many,  per- 
haps most,  cases  of  general  or  special  protective  resemblance. 
A  little  green,  a  little  brown  could  obviously  help  the  insect 
living  in  green  foliage,  or  on  the  ground.  Every  change  of 
tinge  toward  the  general  environing  colour  is  worth  while ;  it 
helps  melt  the  insect  into  its  inanimate  surroundings.  But 
with  mimicry  it  must  be  the  whole  thing  or  nothing;  or  at 
least  near  enough  to  the  whole  thing  to  pass  for  it.  Wolff 
puts  the  objection  about  as  follows :  There  are  compound 
organs  and  complex  adaptations,  whose  complication  (he 
would  better  say,  whose  advantage  due  to  complication)  cart 


DARWINISM   ATTACKED.  51 

only  be  reached  by  a  leap,  while  the  selection  theory  pre- 
supposes slight  gradual  stages  of  complication. 

Wolff  26  expresses  another  phase  of  this  objection  by  re- 
ferring to  a  few  of  many  cases  of  complex  relations  between 

Diffi  ult  of  entirety  distinct  organs  in  the  body,  which 
explaining  com-  relations  constitute  some  of  the  most  important 
amongbaodyn-S  functions  of  the  body.  For  the  successful 
parts  by  selec-  establishment  of  these  relations  it  has  been 
necessary,  as  Wolff  expresses  it,  "that  for  each 
advance  in  development  or  complexity  of  one  definite  pecu- 
liarity in  an  organ  there  must  appear  corresponding  and 
exact  definite  advance  in  development  or  complexity  of  a 
peculiarity  in  another  entirely  distinct  organ."  Wolff's  first 
example  is  the  relationship  existing  between  the  muscles 
and  nerves  of  the  higher  animals.  The  intimate,  delicate, 
and  precise  character  of  the  relations  between  the  nerve-end- 
ings and  the  muscle  cells,  to  be  explicable  by  selection  of 
fortuitous  variations,  must  have  required  coincident  varia- 
tions both  in  structure  and  functions  of  each  muscle  cell  and 
each  nerve-ending  that  are  impossible  to  conceive  of.  "It 
might  be,"  says  Wolff,  "possible  to  picture  the  gradual 
development  of  the  relations  between  one  muscle  cell  and 
one  nerve-ending  on  the  basis  of  a  selection  among  infinitely 
fortuitous  variations,  but  that  such  variation  shall  occur 
coincidently  in  time  and  character  in  hundreds  or  thousands 
of  cases  in  one  organism  is  inconceivable." 

In  the  case  of  organs  whose  functions  are  regulated  from 
a  common  centre,  the  development  of  centre  and  of  organs 
must  have  gone  on  coincidently  and  could  not  have  been 
independent.  The  development  of  the  eye  is  useless  if 
the  development  of  the  optic  centre  did  not  go  hand  in 
hand  with  it.  Without  the  one  the  other  has  no  reason, 
no  significance,  therefore  selection  could  have  brought 
neither  to  its  proper  development  independently.  The 
coincident  appearance,  however,  of  organ  and  centre  can 


52  DARWINISM   TO-DAY. 

be  explained  by  the  selection  theory  only  when  there  is 
postulated  a  definite  degree  of  complexity  of  the  fortu- 
itously appearing  slight  variations,  that  is,  when  this 
theory  is  in  condition  to  assume  that  which  would  be  a 
denial  in  terms  that  variations  are  wholly  fortuitous. 
Wolff  goes  on  to  give  certain  examples  of  such  complex 
relations  which  involve  a  dependence  of  the  use  upon  an 
instinct,  as  the  performance  by  the  queen  honey-bee  of  her 
particular  functions  in  the  hive,  etc. 

"Out  of  this  discussion,"  says  Wolff,  "finally  we  must 
postulate  that  structures  which  are  to  be  explained  by  the 
selection  theory  must  possess  at  the  least  two  certain  charac- 
teristics. Such  a  structure,  namely,  must  occur  but  once 
in  an  organism  [that  is,  must  not  be  a  serially  or  bilaterally 
repeated  organ,  nor  indeed  appear  in  any  condition  of  plural 
number] ;  further,  it  must  not  stand  in  any  necessary  relation 
to  any  other  part  of  the  same  organism,  that  is,  in  a  relation 
which  one  can  interpret  as  a  relation  not  existing  from 
the  beginning,  therefore  one  which  must  be  looked  on  as  an 
acquired  relation.  But  if  we  survey  the  whole  animal  king- 
dom it  will  be  very  difficult  for  us  to  find  any  structures 
which  satisfy  both  these  requirements.  It  might  be  possible 
to  find  some  which  perhaps  seem  to  satisfy  the  second  re- 
quirement, but  with  regard  to  the  first  requirement  I  may 
declare,"  says  Wolff,  "that  there  is  scarcely  a  single  structure 
which  fulfils  it.  Symmetry  alone,  which  rules  almost  all 
organisms,  makes  organs  which  appear  in  the  singular  num- 
ber rarities,  and  even  such  as  the  pancreas,  etc.,  are  com- 
posed of  many  finer  structures,  which  are  homodynamous 
among  themselves.  When  we  find  two  similar  organs  in 
different  animal  groups  we  seek  for  a  causal  explanation  of 
this  similarity  and  find  it  in  common  ancestry.  It  is  absurd 
to  seek  a  causal  explanation  for  the  origin  of  homologous 
structures  and  yet  postulate  a  purely  chance  or  fortuitous 
explanation  for  the  origin  of  homodynamous  structures." 


DARWINISM   ATTACKED.  53 

Another  objection  which  the  study  of  the  utility  of  col- 
our and  pattern  27  also  has  impressed  upon  me  is  that  of  the 
,  carrying  too  far  of  certain  lines  of  modification. 

Objection  based 

on  cver-speciaii-  Classic  examples  are  the  fatal  over-development 
sation.  of  the  antiers  of  the  extinct  irish  stag,  the  un- 

wieldiness  of  the  giant  Cretaceous  reptiles,  the  intimate 
identity  of  the  halves  of  bilaterally  symmetrical  animals. 
Let  me  call  attention  to  an  overdone  case  of  "protective 
resemblance"  among  the  insects.  It  is  that  of  the  famous 
Kallimas,  the  dead-leaf  butterflies  of  the  Malayan  and  gen- 
eral south  tropical  regions.  These  butterflies  (there  are 
several  species  which  show  the  marvellous  imitation)  have 
the  under  sides  of  both  fore  and  hind  wings  so  coloured  and 
streaked  that  when  apposed  over  the  back  in  the  manner 
common  to  butterflies  at  rest,  the  four  wings  combine  to 
Kaliima  the  resemble  with  absurd  fidelity  a  dead  leaf  still 
de^d-leaf  bntter-  attached  by  a  short  petiole  to  the  twig  or  branch. 
I  say  absurd,  for  it  seems  to  me  the  resemblance 
is  over-refined.  Here  for  safety's  sake  it  is  no  question  of 
mimicking  some  one  particular  kind  of  other  organism  or 
inanimate  thing  in  Nature  which  birds  do  not  molest.  It  is 
simply  to  produce  the  effect  of  a  dead  leaf;  any  dead  leaf; 
a  brown,  withering  leaf  on  a  branch.  Leaf-shape  and  gen- 
eral dead-leaf  colour  scheme  are  necessary  for  this  illusion. 
But  are  these  following  things  necessary?  namely,  an 
extraordinarily  faithful  representation  of  mid-rib  and  lateral 
veins  even  to  faint  microscopically-tapering  vein  tips ;  a 
perfect  short  petiole  produced  by  the  apposed  "tails"  of  the 
hind  wings;  a  concealment  of  the  head  of  the  butterfly  so 
that  it  shall  not  mar  the  outlines  of  the  lateral  margin  of  the 
leaf ;  and,  finally,  delicate  little  flecks  of  purplish  or  yellow- 
ish brown  to  mimic  spots  of  decay  and  fungus-attacked  spots 
in  the  leaf  ( !)  and,  as  culmination,  a  tiny  circular  clear 
spot  in  the  fore  wings  (terminal  part  of  the  leaf)  which  shall 
represent  a  worm-eaten  hole,  or  a  piercing  of  the  dry  leaf 


54  DARWINISM   TO-DAY. 

by  flying  splinter,  or  the  complete  decay  of  a  little  spot  due 
to  fungus  growth!  A  general  and  sufficient  seeming  of  a 
dead  leaf,  object  of  no  bird's  active  interest,  yes,  but  not  a 
dead  leaf  modelled  with  the  fidelity  of  the  wax-workers  in 
the  modern  natural  history  museums.  When  natural  selec- 
tion had  got  Kallima  along  to  that  highly  desirable  stage 
when  it  was  so  like  a  dead  leaf  in  general  seeming  that 
every  bird  sweeping  by  saw  it  only  as  a  brown  leaf  clinging 
precariously  to  a  half-stripped  branch,  it  was  natural 
selection's  bounden  duty,  in  conformance  with  its  obligations 
to  its  makers,  to  stop  the  further  modelling  of  Kallima  and 
just  hold  it  up  to  its  hardly  won  advantage.  But  what 
happens?  Kallima  continues  its  way,  specifically  and  ab- 
surdly, dead-leafwards,  until  to-day  it  is  a  much  too  fragile 
thing  to  be  otherwise  than  very  gingerly  handled  by  its 
rather  anxious  foster-parents,  the  neo-Darwinian  selec- 
tionists. 

An  objection  which  was  long  ago  pointed  out,  and  which 
has  been  emphasised  strongly  by  some  biologists  and  almost 
overlooked  by  others,  is  that  of  the  incom- 
Patibility  of  the  results  concerning  the  age  of 
selection  oppor-  life  on  this  earth  as  propounded  by  physicists 
workT t0  d°  ^  anc*  astronomers  with  the  demand  made  by  the 
theory  of  descent.  This  objection  of  the  lack 
of  time  for  the  production  of  the  hosts  of  kinds  of  plants 
and  animals  through  the  slow  workings  of  natural  selection 
was  brought  forward  against  Darwin  from  the  very  begin- 
ning and  has  never  been  given  up.  De  Vries,28  for  example, 
in  a  recent  paper,  refers  to  it  as  follows : 

"The  deductions  made  by  Lord  Kelvin  and  others  from  the 
central  heat  of  the  earth,  from  the  rate  of  the  production  of 
the  calcareous  deposits,  from  the  increase  in  the  amount  of 
salt  in  the  water  of  the  seas,  and  from  various  other  sources, 
indicate  an  age  for  the  inhabitable  surface  of  the  earth  of 
some  millions  of  years  only.  The  most  probable  estimates 


DARWINISM   ATTACKED.  55 

lie  between  twenty  and  forty  millions  of  years.  The  evolu- 
tionists of  the  gradual  line,  however,  have  supposed  many 
thousands  of  millions  of  years  to  be  the  smallest  amount 
that  would  account  for  the  whole  range  of  evolution,  from 
the  very  beginning  until  the  appearance  of  mankind.  This 
large  discrepancy  has  always  been  a  source  of  doubt  and  a 
weapon  in  the  hands  of  opponents  of  the  evolutionary  idea, 
and  it  is  especially  in  this  country  that  much  good  work  has 
been  done  to  overcome  this  difficulty.  The  theory  of  descent 
had  to  be  remoulded.  On  this  point  conviction  has  grown 
in  America  during  the  last  decades  with  increasing  rapidity." 
However  (according  to  a  newspaper  clipping),  Professor 
Lankester,29  a  present-day  Darwinian  champion,  in  the 
course  of  an  interesting  outline  of  the  advance- 

Kadium  a  pos- 
sible answer  to     ment  of  science  in  the  past  twenty-five  years 
the  objection.       whkh  he  gaye  at  ^Q  opening  meeting  of  the 

British  Association  at  York  recently  (September,  1906) 
again  raised  the  question  of  the  age  of  the  earth.  Refer- 
ring to  the  discovery  of  radium  as  one  far  exceeding  in 
importance  all  other  modern  scientific  discoveries  he  said 
that  if  the  sun  contained  a  fraction  of  one  per  cent,  of  radium, 
this  radium  would  account  for  and  make  good  the  heat  that 
is  annually  lost  by  the  sun.  "This  is  a  tremendous  fact, 
upsetting  all  calculations  of  physicists  as  to  duration  in  past 
and  future  of  the  sun's  heat  and  the  temperature  of  the 
earth's  surface.  The  geologists  and  the  biologists  have  long 
contended  that  some  thousand  million  years  must  have 
passed  during  which  the  earth's  surface  has  presented  ap- 
proximately the  same  conditions  of  temperature  as  at  pres- 
ent, in  order  to  allow  time  for  the  evolution  of  living  things 
and  the  formation  of  aqueous  deposits  of  the  earth's  crust. 
The  physicists,"  contended  Professor  Lankester,  "notably 
Professor  Tait  and  Lord  Kelvin,  refused  to  allow  more  than 
ten  million  years  (which. they  have  subsequently  increased 
to  a  hundred  million,  basing  the  estimate  on  the  rate  Of 


56  DARWINISM   TO-DAY. 

cooling  of  a  sphere  of  the  size  and  composition  of  the  earth). 
They  have  assumed  that  its  material  is  self-cooling.  But 
as  Huxley  pointed  out,  mathematics  will  not  give  a  true 
result  when  applied  to  erroneous  data.  It  has  now,  within 
the  last  five  years,  become  evident  that  the  earth's  material 
is  not  self-cooling,  but  on  the  contrary  self-heating,  and 
away  go  the  restrictions  imposed  by  physicists  on  geological 
time.  They  are  now  willing  to  give  us  not  merely  a  thou- 
sand million  years,  but  as  many  more  as  we  want." 

In  this  connection  should  be  mentioned  the  position  taken 
by  Ammon  30  and  others  who  argue  that  the  real  effect  or 

Claim  that  se-  resu^  °^  natural  selection  is  to  preserve  the 
lection  hinders  type  at  the  expense  of  the  variants,  which  would 
moteTspecries-0"  niake  it  a  retarder  rather  than  accelerator  of 
change,  species-change.  Bumpus's 31  observations  on, 

and  conclusions  concerning,  his  storm-beaten  English  spar- 
rows is  an  example  of  what  Ammon  claims  must  be  the 
real  result  of  selection.  Bumpus,  in  statistical  studies  of  the 
variation  of  two  animal  species  introduced  from  Europe  into 
the  United  States,  viz.,  the  English  sparrow  and  the  peri- 
winkle, Littorina  littorea,  shows  that  the  eggs  of  the  sparrow 
and  the  periwinkles  themselves  are  much  more  variable  in 

Bum  us's  ob  America  than  in  their  native  regions,  and  the  au- 
servationson  thor  attributes  this  increased  variability  to  their 
"presumable  emancipation  from  many  of  the  re- 
straining influences  of  natural  selection."  In  the  case  of  the 
English  sparrows,  also,  Bumpus  believes  himself  able  to 
show  on  a  basis  of  the  examination  of  136  birds  brought 
in  wounded  or  stunned  after  a  severe  storm  of  snow,  rain, 
and  sleet  (Feb.  I,  1898),  that  the  sixty-four  birds  that 
perished  (seventy-two  revived),  "perished  not  through  acci- 
dent, but  because  they  were  physically  disqualified,  and  that 
the  birds  which  survived,  survived  because  they  possessed 
certain  physical  characters.  These  characters  enabled  them 
to  withstand  the  intensity  of  this  particular  phase  of  selective 


DARWINISM   ATTACKED.  57 

elimination  and  distinguish  them  from  their  more  unfortu- 
nate companions."  The  fortunate  characters  were  mas- 
culinity, shortness  of  body,  lightness,  longer  humerus,  longer 
femur,  longer  tibio-tarsus,  longer  sternum,  greater  brain 
capacity.  But  more  important  for  survival  than  favourable 
variations  was  the  fact  of  approach  to  the  species  type  or 
mode  of  variability.  The  extreme  variants  perished. 
"The  process  of  selective  elimination  is  most  severe  with  ex- 
tremely variable  individuals,  no  matter  in  what  directions  the 
variations  may  occur.  It  is  quite  as  dangerous  to  be  con- 
spicuously above  a  certain  standard  of  organic  excellence 
as  it  is  to  be  conspicuously  below  the  standard.  It  is  the 
type  that  nature  favours." 

APPENDIX. 

1  For  a  fairly  complete  bibliography,  with  excellent  abstracts,  of 
all    important    critical    discussions    of    Darwinism    since    1895,    see 
L'Annee  Biologique      (ed.  Y.  Delage),  1895-1903;   for  good  bibliog- 
raphy  also   see   Zoologischer  Jahresbericht,    issued   annually.      See 
also  discussions  and  notes  in  such  journals  as  Natural  Science,  Bio- 
logisches  Centralblatt,  Nature,  Science,  American  Naturalist,  etc. 

2  Von   Kolliker,   A.,   "Uber   die   Darwin'sche   Schopfungstheorie," 
Zeitsch.  f.  wiss.  ZooL  Vol.  XIV,  pp.  174-186,  1864. 

3  Korschinsky,  S.,  "Heterogenesis  und  Evolution,"  Naturw.   Wo- 
chenschrift,  Vol.  XIV,  pp.  273-278,  1899. 

*  Morgan,  T.  H.,  "Evolution  and  Adaptation,"  1903.  A  vigorous 
anti-Darwinian  argument,  somewhat  sophisticated  in  its  lawyer- 
like  handling  of  Darwin's  own  words,  but  keen  and  trenchant  in 
its  exposure  of  the  weaknesses  of  the  selection  theories  as  species- 
forming  explanations.  It  is  also  a  brief  for  de  Vries's  theory  of 
species-forming  by  mutation.  (See  chap,  xi  of  this  book.) 

5  "See  Osborn,  H.  R,  "Biol.  Lectures,"  Wood's  Holl  Lab.,  1894, 
pp.  79-100,  for  suggestive  plea  for  the  recognition  of  "the  unknown 
factors  of  evolution." 

6  The  subject  of  variation,  an  absolutely  fundamental  one  in  any 
consideration  of  the  factors  and  mechanism  of  organic  evolution,  has 

a    very   large    literature    pertaining   to    it   which    the 
pers°onSvMiat?on,  serious  student  of  evolution  must  make  considerable 
'  acquaintance  with  at  the  very  outset.     Of  this  litera- 
ture the  following  books  and  papers  may  be  suggested  to  serve  as 


58  DARWINISM   TO-DAY. 

a  means  of  introduction  to  the  subject,  not  alone  in  its  broad  out- 
lines, but  in  its  extensive  ramifications  of  relation  to  other  evolution 
problems.  Some  of  these  books  and  papers  include  extended  biblio- 
graphic lists  sufficient  to  enable  one  to  follow  up  the  subject  in  any 
of  its  special  phases. 

Darwin,  Chas.,  "The  Origin  of  Species,"  1859. 

Darwin,  Chas.,  "The  Variation  of  Animals  and  Plants  under 
Domestication"  (Amer.  ed.),  1868. 

Wallace,  A.  R.,  "Darwinism,"  chaps,  iii  and  iv,  1891. 

Allen,  J.  A.,  "On  the  Mammals  and  Winter  Birds  of  East  Florida," 
Bull  Mus.  Comp.  Zool,  II,  pp.  161-450,  Plates  IV- VIII,  1871. 

Galton,  R,  "Natural  Inheritance,"  1889. 

Bateson,  W.,  "Materials  for  the  Study  of  Variation,"  1894. 

Duncker,  G.,  "Die  Methode  der  Variationsstatistik,"  Archlv  f. 
Entwick.  Mech.,  Vol.  VIII,  pp.  112-183,  1899.  (Full  bibliography.) 

Rosa,  D.,  "La  riduzione  progressiva  della  variabilita  i  suoi  rap- 
porti  coll'  esstinzione  e  coll'  origine  delle  specie,"  1899. 

Conn,  H.  W.,  "The  Method  of  Evolution,"  chap,  iv,  1900. 

Davenport,  C.  B.,  "A  History  of  the  Development  of  the  Quan- 
titative Study  of  Variation,"  Science,  N.  S.,  Vol.  XII,  pp.  864-870, 
1900. 

De  Vries,  H.,  "Die  Mutationstheorie,"  Vol.  I,  pp.  7-150,  pp. 
412-648,  1901. 

Ewart,  J.  C.,  "Variation;  Germinal  and  Environmental,"  Trans. 
Roy.  Dublin  Soc.,  Ser.  II,  Vol.  VII,  pp.  353-378,  1901. 

Vernon,  H.  M.,  "Variation  in  Animals  and  Plants,"  1903. 

Delage,  Y.,  "L'Heredite,"  pp.  283-310,  pp.  826-843,  2d  ed.,  1903. 

Davenport,  C.  B.,  "Statistical  Methods  in  the  Study  of  Varia- 
tion," 2d  ed.,  1904.  (Full  bibliography.) 

Kellogg  and  Bell,  "Studies  of  Variation  in  Insects,"  Proc. 
Wash.  Acad.  Sci.,  Vol.  VI,  pp.  203-332,  1904. 

Lotsy,  J.  P.,  "Vorlesungen  iiber  Descendenztheorien,"  Vol.  I, 
chap,  ix,  1906. 

Biometrika,  1901-1906.  A  journal  devoted  chiefly  to  the  sta- 
tistical study  of  variation. 

7  See  Kellogg,  "Variation  in  Parthenogenetic  Insects,"  Science, 
N.  S.,  Vol.  XXIV,  pp,  695-699,  1906,  in  which  it  is  shown  that  the 

Oases  of  marked  parthenogenetically  produced  drone  honey-bees  vary 
variation  in  par-  much  more  than  do  the  workers  which  are  of  bi- 
thenogenetic  ani-  sexual  parentage,  and  that  parthenogenetically  pro- 
mals>  duced  plant-lice  (Aphidids)  vary  as  markedly  as 

insects  of  bisexual  parentage.  See  also  Warren,  Proc.  Roy.  Soc., 
Vol.  LXV,  1899.  in  which  the  variation  in  parthenogenetic  varia- 
tions of  Daphnia  magna  is  shown  to  be  little,  if  any,  smaller  than 


DARWINISM   ATTACKED.  59 

In  sexually  produced  generations;  also,  Biometrika,  Vol.  I,  pp.  129- 
154,  1902,  in  which  Warren  shows  the  variation  in  parthenogenetic 
series  of  the  plant-louse  Hyalopterus  trirhodus  to  be  as  large  as 
the  variability  exhibited  in  sexual  forms. 

See  also  Haycraft,  J.  B.,  "The  Role  of  Sex,"  Nat.  Science,  Vol. 
VII,  pp.  245-250,  342-344,  1895,  in  which  paper  is  presented  an  ingen- 
ious argument  to  show  that  sexual  reproduction  tends  not  merely  not 
to  increase  variation  but  to  decrease  it :  "the  convergence  to  the  mean 
is,  then,  a  result  of  sexual  reproduction:  it  may  be  termed  the  role 
of  sex,  and  one  indeed  of  no  secondary  order.  The  tendency  con- 
stantly to  vary  is  a  property  inherent  in  protoplasm,  yet  often  for 
long  periods  of  time  the  environment  may  be  the  same.  In  order 
that  a  species  may  continue  to  live  in  such  a  constant  environment, 
the  effects  of  variation  must  be  checked.  Sexual  multiplication,  a 
conservative  function,  antagonises  the  progressive  tendency  of  varia- 
tion." 

Other  naturalists  have  also  held  strongly  to  this  view  of  the  role 
of  amphimixis.  See  Bailey,  L.  H.,  "The  Plant  Individual  in  the 
Light  of  Evolution,"  address  before  the  Biological  Society  of  Wash- 
ington, January  12,  1895,  Science,  N.  S.,  Vol.  I,  p.  281,  1895,  in  which 
paper  the  author  points  out  the  importance  of  a  clear  recognition 
of  the  tremendous  possibilities  and  actuality  of  asexual  variation 
in  plants. 

In  a  paper  by  Winslow  and  Rogers  (Science,  N.  S.,  Vol.  XXL, 
p.  486,  1905),  referring  to  the  classification  of  bacteria,  there  is  the 
following  statement:  "Since  the  swamping  of  minor  differences  by 
sexual  reproduction  is  absent  from  bacteria,  every  inheritable 
variation  is  maintained,  and  instead  of  true  species,  we  find  an  infi- 
nite series  of  minutely  differing  but  constant  races.  The  only  prac- 
tical method  of  handling  and  systematising  these,  is  to  establish  cer- 
tain fairly  distinct  groups  and  types  about  which  the  individual 
variations  may  be  grouped." 

8  By  using  a  large  series  of  individuals,  and  carefully  -tabulating 
the  noted  conditions  of  variation  of  one  or  more  parts,  using,  pref- 
erably, attributes  whose  variability  is  capable  of  being 
matnema1:^ca^y  expressed,  such  as  dimensions,  num- 
of  probabilities,  hers  of  spines,  or  spots,  etc.,  many  students  have 
shown  that  these  variations  seem  to  occur  in  most 
cases  according  to  the  law  of  probabilities,  and  that  a  curve  plotted 
so  as  to  express  graphically  the  actual  conditions  of  variation  for  a 
•given  character  would  be  nearly  identical  with  the  curve  that  could 
be  plotted  so  as  to  express  what  variation  would  exist  in  the  given 
•case  if  this  variation  occurred  exactly  according  to  the  laws  of 
chance.  This  means  that  in  a  thousand  individuals  collected  at 


60  DARWINISM   TO-DAY. 

random  and  examined  for  variation  in  any  character,  say  total 
length  of  body,  not  only  would  there  be  found  a  larger  number  of 
individuals  of  medium  length  than  of  any  other  length  between  the 
two  extremes,  represented  by  the  longest  and  shortest  individuals, 
but  that  the  various  lengths  between  the  mean  and  the  longest  and 
between  the  mean  and  the  shortest,  would  be  represented  by  groups 
of  individuals  regularly  decreasing  in  number  as  the  length  in- 
creased or  decreased  on  either  side  of  the  mean,  but  of  equal  number 
if  compared  at  equal  amounts  of  difference  away  from  the  mean. 

The  curve  expressing  graphically  the  law  of  probabilities  or, 
better,  the  frequency  of  error,  is  determined  by  the  formula  for  this 
frequency  deduced  originally  by  Gauss  at  the  beginning  of  the  last 
century.  It  would  lead  us  too  far  afield  to  reproduce  here  the 
mathematical  proof  of  the  formula  or  method  of  its  determination, 
but  Vernon's  excellent  concrete  illustration  of  how  such  a  formula 
could  be  deduced  directly  from  a  study  of  biologic  variation 
may  be  quoted.  "Supposing,"  says  Vernon  in  " Variation  in  Animals 
and  Plants,"  pp.  n  and  12,  1903,  "a  group  of  developing  organisms 
be  taken,  of  which  the  growth  can  be  affected  in  a  favourable  or  an 
unfavourable  manner  by  their  surroundings.  Let  us  suppose  that 
there  are  twenty  different  agencies,  each  of  which  would  produce 
an  equal,  favourable  effect  on  growth,  and  twenty  which  would  pro- 
duce just  as  great  an  effect  in  the  opposite  direction.  Suppose,  also, 
that  each  organism  is  subjected  to  only  half  of  these  forty  different 
agencies ;  then  it  would  follow,  according  to  the  laws  of  chance, 
that  a  larger  number  of  the  organisms  would  be  acted  upon  by  10 
favourable  and  10  unfavourable  agencies,  than  by  any  other  com- 
bination; i.e.,  they  would,  on  our  hypothesis,  remain  absolutely 
unaffected  in  their  growth.  A  somewhat  smaller  number  would  be 
acted  upon  by  n  favourable  and  9  unfavourable  agencies,  or  on  the 
whole,  would  have  their  growth  slightly  increased.  A  still  smaller 
proportion  would  be  acted  on  by  12  favourable  and  8  unfavourable 
agencies,  or  would  have  their  growth  rather  more  increased.  Finally, 
the  number  of  organisms  acted  on  by  20  favourable  and  o  unfa- 
vourable agencies  would  be  extraordinarily  small,  but  in  this  case  the 
effect  on  growth  would  be  extremely  large.  Similar  relationships, 
only  in  the  reverse  direction,  would  of  course  be  found  in  those 
cases  in  which  the  number  of  unfavourable  agencies  exceeded  the 
number  of  favourable.  If  desired,  the  proportional  numbers  of  organ- 
isms acted  on  by  all  the  different  combinations  of  agencies  may  be 
readily  determined  by  expanding  the  binomial  (]/2  +  ^O20.  It 
is  found,  for  instance,  that  for  each  single  time  the  organisms  are 
acted  on  by  the  whole  20  favourable  agencies,  they  are  acted  on  190 
times  by  18  favourable  and  2  unfavourable;  15,504  times  by  15 


DARWINISM   ATTACKED.  61 

favourable  and  5  unfavourable;  and  no  less  than  184,756  times  by 
10  favourable  and  10  unfavourable.  Let  us  consider  that  the  organ- 
isms acted  on  by  20  favourable  and  o  unfavourable  agencies  have 
their  size  increased  20  per  cent.;  those  acted  on  by  15  favourable 
and  5  unfavourable  by  15  —  5  =  10  per  cent. ;  and  so  on.  If  now 
these  percentage  increments  and  decrements  be  plotted  out  at  equal 
distances  on  a  base  line,  and  ordinates  corresponding  to  the  theo- 
retical frequencies  erected  from  each,  then  by  joining  these  ordinates 
we  shall  obtain  a  curve  which  is  practically  identical  in  form  with 
the  probability  curve  of  the  law  of  frequency  of  error.  Thus,  by  a 
simple  arithmetical  method,  we  obtain  a  series  approximating  more 
and  more  closely  to  the  probability  curve,  the  greater  the  number 
of  times  the  expression  (l/2  -f-  1A)  is  expanded.  Expanded  20 
times,  the  average  error  is  less  than  .5  per  cent.,  and  for  a  greater 
number  of  times  it  becomes  rapidly  smaller  and  smaller." 

This  discovery  and  formulation  of  the  law  of  individual  varia- 
tion— namely,  that  such  variation  occurs  according  to  the  law  of 
probabilities — was  first  made  by  the  Belgian  anthro- 
Pol°gist>  Quetelet  ("Lettres  sur  la  theorie  des  Proba- 
ation  according  bilites,"  Brussels,  1846),  on  a  basis  of  the  examina- 
to  the  law  of  tion  of  the  height  and  chest  measurements  of  soldiers, 
chance,  jt  was  jater  elaborately  confirmed  by  Francis  Galton 

(numerous  papers  and  the  book,  "Natural  Inheritance,"  1870-1890), 
by  quantitative  determinations  of  the  height,  weight,  span  of  arms, 
breathing  capacity,  strength  of  pull,  strength  of  squeeze,  swiftness 
of  blow,  and  keenness  of  sight  in  men  and  women.  It  has  been 
most  illuminatingly  discussed  by  Karl  Pearson  in  "The  Chances  of 
Death,  and  other  Studies  in  Evolution,"  2  vols.,  1897.  Since  then 
the  recognised  necessity  of  a  more  thorough  study  and  understand- 
ing of  variation,  as  the  indispensable  foundation  of  species-forming 
has  led  to  a  large  development  of  the  statistical  and  mathematical 
study  of  variation,  under  the  name  of  biometry,  a  study  largely  due 
to  the  initiative  and  genius  of  the  English  mathematician  and  natural 
philosopher,  Karl  Pearson  (numerous  papers  from  1894  to  present). 
Most  of  the  methods  and  formulae  for  determining  precise  mathe- 
matical expression  of  variation  conditions  have  been  devised  by  him. 
These  methods  and  formulae  permit  of  an  actual  mathematical  com- 
parison of  variation  among  various  parts  in  one  species  (immensely 
enlarging  our  definite  knowledge  of  structural  correlations),  or 
among  similar  or  wholly  different  parts  in  various  species.  With 
the  statistical  facts  or  data  of  variation  thus  put  into  precise  mathe- 
matical expression,  these  expressions  may  be  submitted  to  a  deal 
of  independent  mathematical  treatment;  rather  bewildering,  it  must 
be  confessed,  to  most  biologists,  but  presented  by  the  biometricians 


62  DARWINISM   TO-DAY. 

as  the  first  step  toward  making  biology,  in  part,  at  least,  an  exact 
science.  But  there  is  no  question  at  all  that  the  statistical  and 
quantitative  study  of  variation,  and  the  use  of  authoritatively 
deduced  mathematical  expressions  (and  the  graphic  representation 
of  these  by  plotted  frequency  curves,  polygons,  etc.),  have  immensely 
advanced  our  understanding  of  variation  conditions,  and  given  us 
defmiteness  and  concreteness  in  a  fundamental  field  of  evolution 
study,  where  before  were  a  mass  of  uncoordinated  data  and  a  haze 
of  loose  generalising. 

9  Bateson,  Wm.,  "Materials  for  the  Study  of  Variation,"  1894. 

10  See  Kellogg  and  Bell,  "Studies  of  Variation  in  Insects,"  Proc. 
Wash.  Acad.  Sci.,  Vol.  VI,  pp.  203-332,  1904,  in  which  are  discussed 

(pp.  257-273)  variation  conditions  existing  in  the  lady- 
triviSvariations  ^1T<^  Beetle,  Hippodamia  convergent.  The  variations 

in  the  number  and  character  of  the  elytral  pattern 
(small  black  spots  on  a  brown  ground)  noted  in  a  thousand  speci- 
mens examined,  were  such  that  eighty-four  "aberrations,"  or  pat- 
tern-variates,  could  be  distinguished  and  described,  and  yet,  an 
intensity  of  scrutiny  demanding  the  use  of  a  lens  was  necessary  to 
distinguish  properly  these  varying  types.  Such  a  scrutiny,  needless 
to  say,  will  never  be  given  these  beetles  by  bird  or  lizard,  the  active 
agents  representing  natural  selection,  as  far  as  pattern  is  to  be 
tested.  Nevertheless,  these  pattern  variations,  if  not  so  completely 
connected  by  gradatory  steps,  would  be  exactly  the  characters  on 
which  several  Hippodamia  species  would  be  based,  for  they  range  all 
the  way  from  no  spots  to  eighteen  spots,  although  twelve  is  the 
species  character  of  convergent. 

11  Romanes  discusses  this  subject  of  the  indifference,  or  triviality, 
of  many  specific  characters  at  some  length  in  chap,  vii  of  his  "Dar- 
win and  After  Darwin,"  II,  "Post-Darwinian  Questions,"  "Heredity 
and  Utility,"  1895. 

12  Conn,  H.  W.,  "Method  of  Evolution,"  pp.  78-83,  1900. 

1S  Nageli,  Carl,  "Mechanisch-physiologische    Theorie  der  Abstam- 

mungslehre,"   1884.     Nageli,  an  eminent  botanist,   formulated  many 

NSgeli's  seven    vears  a&°  tne   following  famous   seven  objections  to 

objections  to  spe-  the  natural   selection  theory  of  species-forming    (pp. 

cies-forming  by     289-290)  : 

selection,  «Ich   hebe    fo]gen(je   sjeben   Gesichtspunkte    hervor, 

welche  uns  die  Abstammung  durch  Zuchtwahl  unannehmbar  machen  : 
"i.  Beziiglich  der  allgemeinen  Bedeutung  der  Selectionstheorie 
ist  die  unbestimmte  Wirkung  unbestimmter  Ursachen  und  die  dem 
Zufall  allzusehr  iiberlassene  Entscheidung  durch  die  natiirliche 
Zuchtwahl  unserem  naturwissenschaftlichen  Bewusstsein  weniger 
zusagend.  Ferner  setzt  sich  die  Selecticnstheorie,  welche  ihrem 


DARWINISM   ATTACKED.  63 

Princip  gemass  nur  nach  dem  erreichten  Nutzen  einer  Erscheinung 
fragt,  um  dieselbe  zu  rechtfertigen,  in  Widerspruch  mit  der  wahren 
und  exacten  Naturforschung,  welche  vor  allem  die  bewirkenden  Ur- 
sachen  der  Dinge  zu  erkennen  sucht. 

"2.  Die  Folgerung  von  der  (kiinstlichen)  Rassenbildung  auf  die 
(natiirliche)  Varietatenbildung,  welche  die  Grundlage  der  Selec- 
tionstheorie  ausmacht,  ist  unzulassig,  da  beide  wesentlich  verschie- 
den  sind  und  namentlich  sich  riicksichtlich  der  Kreuzung  ungleich 
verhalten.  Die  Varietaten  namlich  vermischen  sich  sehr  schwer  mit 
einander  und  nehmen  kein  fremdes  Blut  in  irgend  wirksamer  Menge 
auf,  werden  somit  auch  durch  die  ihnen  gebotene  Gelegenheit  zur 
Kreuzung  nicht  verandert ;  mit  diesen  Eigenschaften  stimmen  ihre 
Vorkommensverhaltnisse  genau  iiberein. 

"3.  Niitzliche  Veranderungen  konnen  erst,  wenn  sie  eine  bemerk- 
bare  Hohe  erreicht  haben  und  in  zahlreichen  Individuen  vorhanden 
sind,  eine  ausgiebige  Verdrangung  der  Mitbewerber  bewirken.  Da 
sie  aber  im  Anfange  durch  eine  lange  Reihe  von  Generationen  jeden- 
falls  noch  sehr  unbedeutend  und  nach  der  Selectionstheorie  auch  nur 
in  einer  kleinen  Zahl  von  Individuen  vertreten  sind,  so  bleibt  die 
Verdrangung  aus  und  eine  naturliche  Zuchtwahl  kommt,  da  ihr  der 
wirksame  Hebel  mangelt,  iiberhaupt  nicht  zu  Stande. 

"4.  Die  Ernahrungseinfliisse,  welche  die  Selectionstheorie  voraus- 
setzt,  bewirken  thatsachlich  keine  erblichen  Veranderungen,  und 
wenn  sie  es  thaten,  so  konnte  eine  Steigerung  der  begonnenen  Aban- 
derung  nicht  eintreten,  weil  die  unvermeidliche  Kreuzung  eine 
naturliche  Zuchtwahl  unmoglich  machen  wiirde.  Ferner  lasst  sich 
aus  den  unbestimmten,  in  alien  denkbaren  Richtungen  wirkenden 
Ernahrungseinfliissen  der  so  stetige  phylogenetische  Fortschritt  zu 
einer  complicirteren  Organisation  nicht  erklaren.  Ebenso  wenig 
werden  durch  dieselben  die  Erscheinungen  der  Anpassung  verur- 
sacht ;  dies  ergibt  sich  einerseits  aus  dem  Umstande,  dass  Gebrauch 
und  Nichtgebrauch  die  Zu-  und  Abnahme  der  Organe  bedingen,  da 
diese  Ursache  fur  sich  vollkommen  ausreicht  und  daher  die  Mit- 
wirkung  einer  zweiten  andersartigen  Ursache  ausschliesst, — und 
andrerseits  durch  den  ferneren  Umstand,  dass  Anfange  von  Organen 
bis  zu  der  Grosse,  wo  sie  in  Gebrauch  kommen  und  ihre  Niitzlich- 
keit  zu  erproben  vermogen,  mangeln,  obgleich  sie  durch  die  Ernah- 
rungseinfliisse in  Menge  hervorgebracht  werden  miissten. 

"5.  Die  Eigenschaften  der  Organismen  miissten  in  Folge  der 
natiirlichen  Zuchtwahl  um  so  constanter  sein,  je  niitzlicher  sie  sind, 
und  Einrichtungen,  die  keinen  Vortheil  gewahren,  konnten  keine 
Bestandigkeit  erlangen.  Im  Widerspruche  hiermit  gehoren  gewisse. 
rein  morphologische,  mit  Riicksicht  auf  den  Nutzen  indifferente 
Merkmale  zu  den  allerbestandigsten. 


64  DARWINISM   TO-DAY. 

"6.  Aus  der  Selectionstheorie,  nach  welcher  von  den  eintretenden 
richtungslosen  Veranderungen  bloss  die  niitzlichen  festgehalten  wiir- 
den,  lassen  sich  weder  die  Divergenz  der  Reihen  in  den  organischen 
Reichen,  noch  die  bestehenden  Liicken  in  und  zwischen  den  Reihen 
erklaren,  indem  vielmehr  eine  netzformige  Anordnung  der  Sippen 
zu  Stande  kommen  musste. 

"7.  Ebenso  widersprechen  jener  Theorie  das  Nichtvorhandensein 
der  von  ihr  behaupteten  gegenseitigen  Anpassung  der  Bewohner  eines 
Landes  und  die  bestehenden  Naturalisationen  fremder  Erzeugnisse. 

"Diese  Einwurfe  gegen  die  Selectionstheorie,  die  ich  hier  bloss 
ganz  allgemein  formulirt  habe,  sollen  im  folgenden  des  Naheren 
begriindet  werden." 

14  Wolff,  G.,  "Beitrage  zur  Kritik  der  Darwin'schen  Lehre,"  1898. 
From  this  caustic  attack  on  the  Darwinian  position,  I  quote  as  fol- 
lows (pp.  56-57)  : 

"Wenn  wir  sagen,  die  Selektion  schafft  Zweckmassiges  dadurch, 
dass  eben  nur  das  Zweckmassige  erhalten  wird,  das  andre  zu  Grunde 
geht,   so  wird  in   dieser  Fassung   das   Zweckmassige 
Wolffs  attack    natiirlich  vorausgesetzt,  aber  nicht  seih  Zustandekom- 
on  the  selection-    men  erklart.    Dass  Zweckmassiges  iiberhaupt  da  war, 
ists'  assumption     .       .       ,  ..  ,  ~      ,  11-1-, 

of  the  appearance  lst  im  nocnsten  Grade  unwahrscheinhch  und  unver- 
at  the  right  time  standlich.  Mochte  auch  unter  den  vielen  Variie- 
of  the  needed  rungen  manchmal  etwas  Zweckmassiges  zufallig 
variation.  vorgekommen  .sein,  so  ist  die  Wahrscheinlichkeit  eines 

solchen  Eintreffens  so  gering,  dass  ich  nicht  das  Recht 
habe,  diesen  Faktor  als  einen  gegebenen  in  meine  Rechnung  ein- 
zusetzen.  Diese  Wahrscheinlichkeit  sucht  nun  der  Darwinismus 
dadurch  zu  vergrossern,  dass  er  alle  moglichen  Falle  annimmt,  unter 
welchen  naturlich  auch  das  Zweckmassige  als  Spezialfall  enthalten 
sein  muss.  Der  Darwinismus  sucht  also  den  Treffer  sich  dadurch 
zu  sichern,  dass  er  den  ganzen  Gliickshafen  mit  nach  Hause  nimmt. 

"Um  ein  Beispiel  zu  nehmen :  es  sei  von  Vorteil,  dass  die  Schna- 
belform  entsteht,  wie  sie  beim  Kreuzschnabel  vorhanden  ist.  Der 
Darwinismus  nimmt  an,  dass  durch  gliickliche  Variierung  ein  bezw. 
mehrere  oder  sogar  viele  gekreuzten  Schnabel  auftraten.  Sagt  nun 
der  Gegner:  das  spontane  Auftreten  einer  Schnabelkreuzung  scheint 
mir  so  unwahrscheinlich,  dass  ich  diese  Voraussetzung  eben  nicht 
zugebe,  so  antwortet  der  Darwinist:  unter  alien  moglichen  Schnabel- 
variierungen  ist  auch  der  gekreuzte,  darf  ich  alle,  so  darf  ich  auch 
diesen  voraussetzen ;  da  aber  die  Variierung,  wie  die  Beobachtung 
lehrt,  nach  alien  Richtungen  beliebig  wirkt,  so  sind  alle  Variierungen 
moglich,  folglich  darf  ich  auch  jene  spezielle  voraussetzen. 

"Der  Gegner  wiirde  jetzt  vielleicht  so  erwidern :  Gewiss,  moglich 
sind  alle  Variierungen,  aber  gegeben  ist  deren  doch  immer  nur  eine 


DARWINISM    ATTACKED.  65 

begrenzte  Anzahl.  Die  Zahl  aller  moglichen  Variierungen  ist  =  « , 
die  Zahl  der  gegebenen  ist  eine  endliche  Grosse.  Die  Wahrschein- 
lichkeit  des  Eintretens  einer  speziellen  zweckmassigen  Variierung 
(in  unserm  Bei^piel  der  zweckmassigen  Schnabelkreuzung)  ist  End- 
liches  dividiert  durch  Unendliches,  d.  h.  eine  Zahl,  welche  sich  der 
Null  ohne  Ende  nahert;  mithin  ist  die  Wahrscheinlichkeit,  dass 
unter  den  gegebenen  Fallen  sich  eine  giinstige  Variierung  befindet, 
so  ungeheuer  klein,  dass  nicht  die  geringste  wissenschaftliche  Be- 
rechtigung  besteht,  den  betreffenden  Fall  vorauszusetzen.  Und  nun 
wurde  allerdings  demjenigen  Darwinisten,  welchem  die  Kiihnheit 
fehlte,  die  Zahl  der  ihm  zur  Verfiigung  stehenden  Variierungen  ein- 
fach  =  CQ  zu  setzen,  wohl  kaum  etwas  andres  iibrig  bleiben,  als  sich 
darauf  zu  berufen,  dass  es  eine  Sorte  von  Variierungen  giebt,  bei 
denen  die  Zahl  der  gegebenen  Falle  gross  genug  ist,  um  alle  mogli- 
chen zu  enthalten,  gross  genug  also,  um  die  Voraussetzung  jedes 
einzelnen  wissenschaftlich  zu  rechtfertigen,  namlich  diejenigen  Vari- 
ierungen, welche  nur  in  graduellen  Veranderungen  bestehen,  bei 
denen  es  sich  also  nur  darum  handelt,  dass  ein  Vorhandenes  grosser 
oder  kleiner  wird.  Hier  ist  die  Zahl  der  moglichen  Falle  gleich  2, 
die  der  gegebenen  ebenfalls,  die  Wahrscheinlichkeit,  sich  unter  den 
gegebenen  zu  befinden,  ist  also  fur  jeden  der  moglichen  Falle 
gleich  i." 

15  Kronig,  "Das  Dasein  Gottes  und  das  Gliick  des  Menschen,"  p. 
109,  1874. 

16  Weismann,  Aug.,  "On  Germinal  Selection  as  a  Source  of  Defi- 
nite Variation,"  trans.  McCormack,  p.  3  (preface),  1896. 

17  Pfeffer,  Georg,  "Die  Umwandlung  der  Arten,"  1894. 

18  Wolff,  G.,  "Der  gegenwartige  Stand  des  Darwinismus,"  1896; 
also,  "Beitrage  zur  Kritik  der  Darwin'schen  Lehre,"  1898. 

19  Morgan,  T.  H.?  "Evolution  and  Adaptation,"  1903. 

20  Kellogg   and    Bell,    "Studies    of   Variation    in    Insects,"    Proc. 
Wash.   Acad,  Sci.,   Vol.   VI,  pp.  203-332,    1904.     The   following   is 
quoted  from  pp.  330-332: 

"Insects  are  bilaterally  symmetrical  and  metameric  animals.  There 
are  thus  right  and  left  and  fore  and  aft  structural  correlations.  Do  the 
Example  of  non-  va"ati°ns»  continuous  and  discontinuous,  show  similar 
correlated  varia-  bilateral  and  metameric  correlation  ?  Evidence  regard- 
Mlity  in  bilater-  ing  this  question  will  be  found  on  many  pages  in  the 
Present  paper,  right  and  left  correlation,  at  least,  hav- 
ing been  considered  and  briefly  discussed  in  connection 
with  almost  all  of  the  various  cases  studied.  And  the  evidence  is 
curiously  conflicting.  For  example,  in  the  male  black  ant  in  which 
were  studied  the  variations  of  the  venation  and  number  of  hooks,  a 
close  correlation  in  the  variation  conditions  of  right  and  left  wings 


66  DARWINISM   TO-DAY. 

exists.  On  the  other  hand,  in  the  honey-bee  the  bilateral  correla- 
tion of  variation  seems  surprisingly  small  (see  pp.  214-222).  In 
the  case  of  variations  in  pattern,  also,  there  is  no  uniformity  among 
the  various  cases  studied.  In  Hippodamia  convergent  (p.  257  et 
seq.)  the  two  elytra  show  pattern-variations  quite  independently; 
in  Diabrotica  soror  (p.  274  et  seq.),  on  the  contrary,  there  seems 
to  be  a  marked  right  and  left  correlation  in  the  elytral  pattern- 
variation.  In  the  cases  of  the  variation  in  number  of  tibial  spines 
on  the  right  and  left  hind. tibiae  of  locusts  (p.  301)  and  cicadas  (p. 
306),  we  have  simply  made  a  brief  statement,  in  each  case,  of  the 
actual  conditions  of  correlation,  leaving  the  reader  to  draw  his  own 
conclusions.  In  the  case  of  the  variation  in  actual  and  relative 
length  of  the  antennal  segments  of  the  scale  insect,  Ceroputo  yucca 
(?)  (P-  3IO)»  there  is  a  surprising  lack  of  correlation  between  the 
right  and  left  antennae. 

"We  have  not  attempted  to  determine  the  mathematical  expression 
(coefficient  of  correlation)  for  any  of  the  cases  studied.  The  data 
presented,  however,  will  enable  any  biometrician,  who  sees  an 
advantage  in  doing  this,  to  do  it.  But  without  checking  our  results 
by  the  use  of  that  method  there  seems,  on  the  whole,  to  be  a  sur- 
prising lack  of  that  fine  degree  of  correlation  in  variation  which 
we  should  expect  to  find  existing,  if  we  believe  that  the  actual 
existing  conditions  of  structure  and  pattern  in  these  bilaterally  sym- 
metrical animals  are  an  expression  of  the  result  of  the  action  of 
a  rigorous  natural  selection.  If  one  condition  of  pattern  or  structure 
is  the  most  advantageous  (of  the  many  conditions  which  selection 
among  a  host  of  fluctuating  variations  could  have  established), 
surely  this  condition  ought  to  be  pretty  closely  similar  on  both  sides 
of  the  insect.  That  as  much  bilateral  variety  as  actually  exists, 
in  many  of  the  species  examined  by  us,  should  exist — a  variety 
comparable  in  certain  cases  even  with  the  degree  of  variety  revealed 
by  the  comparison  of  considerable  series  of  individuals — is  a  state  of 
affairs  that  only  confirms  us  in  the  belief  that  these  innumerable 
small  continuous  variations,  on  which  for  so  long  the  thorough- 
going selectionists  have  put  their  faith  as  the  sufficient  bases  for 
natural  selection's  species-forming  work,  are  clearly  not  competent 
to  serve  as  such  bases.  If  these  'continuous'  variations  are  the  foun- 
dation stones  of  new  species,  some  other  agents  than  selection  must 
be  found  or  invoked  to  build  several  courses  on  them,  to  produce 
some  cumulation  of  them,  before  natural  selection  finds  them  of 
that  life-and-death  worth  which  is  the  prerequisite  for  her  potent 
interference." 

21  Henslow,  the  botanist,  has  maintained  a  constant  attitude  of 
antagonism  to  natural  selection  on  the  basis  of  his  belief  that  the 


DARWINISM   ATTACKED.  67 

complex  correlations  of  floral  structures  cannot  possibly  be  accounted 
for  by  the  natural  selection  of  fortuitous  variations.  Henslow's 

_          ,  observations    and    ideas    are    exploited    in    detail    in 

tagonismtoselec- two  books  called,   "The  Origin  of  Floral   Structures 

tion  as  explain-     through     Insect     and     Other     Agencies,"     1895,     and 

er  of  floral  corre-   «The  Origin  of  Plant  Structures  by  Self- Adaptation 

to  the  Environment,"  1895. 

22  Wolff,  G.,  "Beitrage  zur  Kritik  der  Darwin' schen  Lehre,"  p. 
6,  1898. 

28  Wolff,  G.,  "Beitrage  zur  Kritik  der  Darwin'schen  Lehre,"  1898. 
I  quote  the  following,  pp.  6-8 : 

"Solche   Erscheinungen,  welche  der  Erklarung  durch  die   Selek- 

tionstheorie   widerstreben,    weil    sie    hier    eine   gesetzmassige   kom- 

plizierte  Veranderung  der  Formen  voraussetzen  wiirde, 

Wolff's  objection  statt  sie  zu  erklaren,  sind  aber  nicht  etwa  nur  verein- 

to  the  necessary    zejte    Falle,    sondern    von    solchen    wird    die    ganze 

fdenticalTnd  co-   Formgestaltung    beherrscht,    wie    z.    B.    von    symme- 

incident  varia-      trischer  Anlage.     Auch  brauchen  wir  uns  bei  dieser 

tion  in  repeated    Betrachtung    nicht    nur    auf    solche    Gebilde    zu    be- 

stmctnres  as         schranken,  die  in  geringer  Mehrheit  vorhanden  sind, 

feathers,  sales,     sondem  es  giebt  ja  Gebilde)  die  in  hundert-,  ja  tau- 

sendfacher  Anzahl  an  einem  und  demselben  Or- 
ganismus  sich  finden,  wie  Schuppen,  Haare,  Federn.  Betrachten 
wir  z.  B.  gerade  die  Federn.  Wie  viel  Millionen  Variierungen 
musste  eine  Reptilienschuppe  durchmachen,  bis  sie  sich  in  eine 
Feder  verwandelt  hatte,  vollends  noch  in  ein  so  kompliziertes  Gebilde 
wie  z.  B.  die  Schwanzfeder  des  Pfaues.  Aber  dies  ware  immer 
noch  nach  der  Selektionstheorie  erklarlich.  Nicht  erklarlich  dage- 
gen  ware,  dass  die  anderen  Schwanzfedern  immer  gleichzeitig 
dieselben  Variierungen  durchmachten.  Ein  Gesetz,  welches  ein 
einheitliches  Variieren  dieser  Hautgebilde  vorschreibt,  giebt  es 
nicht,  denn  es  variieren  ja  nicht  alle  gleich.  Es  entstehen  viele 
gleiche  Flaumfedern,  viele  gleiche  Schwanzfedern  etc.,  an  einigen 
Stellen  bleiben  die  Schuppen  sogar  erhalten,  namlich  an  den  hinteren 
Extremitaten. 

"Wir  konnen  noch  weiter  gehen.  Eine  Masse  von  einzelnen  Zel- 
len  musste  bei  den  verschiedenen  Differenzierungen,  bei  Entstehung 
des  Darms,  des  Nervensystems,  der  Muskulatur  etc.  in  ganz  genau 
der  gleichen  Weise  variieren.  Wenn  wir  hier  die  Selektionstheorie 
zur  Erklarung  herbeiziehen  wollen,  so  ist  die  Kompliziertheit  des 
einzelnen  Variierungsinkrementes  so  gross,  dass  damit  die  ganze 
weitere  Erklarung  iiberflussig  wird. 

"Interessant  sind  ferner  solche  homodynamen  Gebilde,  die  nicht 
zu  gleicher  Zeit  auftreten,  wie  der  dritte  halbzirkelformige  Kanal 


68  DARWINISM   TO-DAY. 

im  Gehororgan  der  Wirbeltiere,  welcher  bekanntlich  erst  in  der 
Klasse  der  Fische  auftritt.  Dieser  dritte  Kanal  1st  den  beiden 
andern  vollig  gleich,  hat  Crista,  Ampulle,  Macula  etc.,  ist  aber 
spater  entstanden;  die  namlichen  zufalligen  Variierungen,  die 
stattfanden  bei  der  Entstehung  der  beiden  ersten  Kanale,  mussten 
viele  Generationen  spater  ganz  genau  in  derselben  Art  sich  wieder- 
holen !  Dass  diese  Variierungen  wieder  auftreten,  dies  erklart  die 
Darwinsche  Lehre  nicht;  denn  die  Selektion  kann  ja  keinen  Ein- 
fluss  auf  die  Variierung  ausiiben. 

"Aehnlich  sind  die  Resultate  der  Kowalevskyschen  Untersuch- 
ungen  iiber  fossile  Huftiere  zu  betrachten,  welche  sich  auf  die  im 
Lauf  der  phylogenetischen  Entwicklung  stattgehabten  Umwand- 
lungen  des  Extremitatenskelettes  dieser  Tiere  beziehen.  Hier  kann 
bekanntlich  eine  allmahlich  eintretende  Verringerung  der  Anzahl 
der  Metatarsal-  und  Metakarpalknochen  sovvie  der  Phalangen 
verfolgt  werden.  Diese  Verringerung  tritt  zuerst  an  den  hintern, 
erst  spater  an  den  vordern  Extremitaten  auf!" 

24  A  moth,  Phryganidia  calif  arnica,  whose  larvae  live  abundantly 
on  the  oak  trees  in  California,  shows  very  clearly  how  a  conspicuous 
Example  of  mal-  disadvantage  does  not  seem  to  interfere  much  with 
adaptation  in  egg- successful  life;  for  the  "success"  of  this  moth  is  only 
laying  habit  of  too  well  proved  by  the  serious  injuries  which  it  pro- 
^063'  because  of  its  Sreat  numbers,  on  the  beautiful 
trees  it  infests.  For  several  years  the  live-oaks  and 
white  oaks  of  the  Santa  Clara  Valley  were  defoliated  to  a  dangerous 
extent.  The  life  history  of  the  moth  is  told  in  detail  in  "The 
Calif ornian  Phryganidian,"  by  Kellogg  and  Jack,  Proc.  Cal.  Acad. 
Sci.,  Ser.  2,  Vol.  V,  pp.  562-570,  1895.  From  this  account  I  quote  the 
following:  "Although  most  abundant  on  the  live-oaks  (Q.agrifolia), 
the  larvae  attack  other  oaks.  We  have  found  them  on  Quercus 
lobata,  Q.  kelloggii,  Q.  dumosa,  and  Q.  douglasii.  The  live-oaks  in 
this  vicinity  begin  to  put  out  new  leaves  about  January  i,  but  in 
the  case  of  many  of  the  trees  badly  defoliated  by  the  larvae  in  the 
autumn,  new  leaves  appeared  much  earlier  than  the  first  of  Janu- 
ary. The  wintering  of  the  insect  in  a  larval  condition  is  only  possi- 
ble in  the  evergreen  oaks,  and  they  are  thus  the  natural  and  usual 
host  of  the  pest.  At  the  time  of  the  hatching  of  the  first  of  the 
autumn  brood  of  eggs  (latter  part  of  November),  the  leaves  of  the 
deciduous  oaks  begin  to  fall.  But,  oddly,  the  eggs  were  found  to 
be  deposited  on  the  leaves  of  both  the  white  oak  and  Douglas's  oak 
(deciduous  oaks),  and  the  larvae  hatched  only  to  die  of  starvation. 
By  this  suicidal  means  the  pest  aids  in  depleting  its  own  numbers. 
The  new  leaves  of  the  deciduous  oaks  appear  about  April  i.  before 
the  eggs  for  the  summer  brood  of  larvae  are  deposited.  These  eggs, 


DARWINISM   ATTACKED.  69 

therefore,  can  safely  be  laid  on  the  leaves  of  these  trees,  but  the 
eggs  laid  by  the  fall  moths  on  the  foliage  of  these  trees  give  up  their 
young  to  certain  destruction." 

25  Mivart,  St.  G.,  "On  the  Genesis  of  Species,"  1871. 

26  Wolff,  G.,  "Beitrage  zur  Kritik  der  Darwin'schen  Lehre,"  p.  8 
ff.,  1898. 

27  In    Piepers,    M.    C,    "Mimikry,    Selektion    und    Darwinismus," 
1903,   the  author   strongly   antagonises  the   Darwinian   explanation 

,  of  protective  warning  and  mimicking  colour  patterns, 

tagonism  to  selec-  Piepers  claims  to  show  ( i )  that  the  so-called  mimicry 
tion  explanation  is  a  phenomenon  or  appearance  whose  biological 
of  colour  and  pat-  value  is  greatly  over-praised;  (2)  that  the  causes  of 
terno  insects,  ^^  appearance  are  not  entirely  known,  yet  can  in 
most  cases  be  very  well  explained  without  having  recourse  to  this 
natural  selection  theory;  and  (3)  that,  therefore,  mimicry  makes 
natural  selection  in  no  wise  necessary,  and  hence  lends  no  basis 
for  its  establishing.  The  author  also,  in  a  long  discussion  of  nearly 
one  hundred  pages,  criticises  adversely  the  selection  theories  and 
Darwin  in  general.  He  holds  that  the  Darwinian  theory  of  species- 
building  from  varieties  is  very  ill-grounded,  but  finds  also  de 
Vries's  mutations-theory  incompetent  to  explain  species,  at  least,  in 
the  large  degree  in  which  they  actually  exist.  The  author  presents 
a  theory  or  explanation  of  his  own  for  species-forming,  which  is 
essentially  this:  Variation  is  not  simply  a  fluctuation  about  a  stable 
mean ;  it  is  evolution  in  small  steps.  Evolution  is  the  principle  of 
life ;  it  is  determinate,  i.e.,  progressive,  yet  with  rapid,  slow,  or  even 
standstill  periods.  There  are  differences  in  the  rapidity  of  evolu- 
tion among  similar  groups,  as  classes,  orders,  families,  genera, 
species,  races,  even  individuals,  and  the  two  sexes  of  a  kind.  This 
accounts  for  the  great  variety  of  life.  There  is  a  great  variety  of 
stages  of  evolution  rather  than  a  great  variety  of  adaptation. 

28  De  Vries,  Hugo,  "The  Evidence  of  Evolution,"  Science,  N.  S., 
Vol.  XX,  pp.  395-401,  1904. 

29  Lankester,  Prof.  Ray,  Address  by,  reported  in  the  London  Mail, 
September,  1906. 

30  Ammon   O.,   "Der   Abanderungsspielraum,"   Naturw.    Wochen- 
schr.,  Vol.  XI,  pp.  I37-I43>  I49-I55,  161-166,  1894. 

81  Bumpus,  H.  C.,  "The  Variations  and  Mutations  of  the  Intro- 
duced Sparrow,  Passer  domesticus,"  in  Biological  Lectures,  Wood's 
Holl  Laboratory,  1897;  also,  "The  Elimination  of  the  Unfit  as  illus- 
trated by  the  Introduced  Sparrow,  Passer  domesticus,"  in  Biological 
Lectures,  Wood's  Holl  Laboratory,  i8g$;  also,  "The  Variations  and 
Mutations  of  the  Introduced  Littorina,"  Zool.  Bull.,  Vol.  I,  pp.  247- 
259,  1898. 


CHAPTER  IV. 

DARWINISM  ATTACKED  (CONTINUED):  THE 
THEORY  OF  NATURAL  SELECTION  (CON- 
TINUED). 

CERTAIN  objections  urged  by  various  authors  may  be  said 

to  concern  themselves  more  with  the  character  of  the  varia- 

Objection  based  tions  themselves  and  the  possibilities  of  their 

on  the  linear  and  accurnulation  by  selection,  than  with  the  manner 
quantitative  and 

non-qnaiitative    of  their  occurrence.     For  example,  de  Vries 
tnatfnTvaria-110"  denies   tne   species-forming   capacity   of   Dar- 
tions,  winian    selection    of    Darwinian    (fluctuating) 

variation,  on  the  ground  that  these  variations  are  only 
"linear,"  and  thus  cannot  afford  a  basis  for  the  creation  of 
new  forms.  Already  existing  bodies,  organs,  and  parts 
can  be  enlarged  or  made  smaller,  made  smoother  or  rougher, 
made  bluer  or  less  blue,  greener  or  less  green,  that  is  de- 
veloped plus-ward  or  minus-ward,  but  by  this  nothing  really 
'new  is  created.  But,  declares  de  Vries,  the  differentiation 
of  organs  consists,  taken  by  and  large,  in  the  development 
of  actually  new  characteristics ;  therefore  in  such  material  as 
that  presented  by  the  linear  variations  of  Darwin,  selection 
cannot  have  the  necessary  basis  for  this  production  of  new 
characteristics. 

Gustav  Wolff  2  reiterates  the  same  objection  in  his  declara- 
tion that  while  the  theory  of  natural  selection  may  get  on 
decently  well  when  modifications  embodying  only  quan- 
titative changes  in  parts  or  organs  are  concerned,  it  is  com- 
pletely at  a  loss  to  account  for  modifications  or  adaptations 
requiring  as  basis  qualitative  changes.  Even  the  warmest 

70 


DARWINISM   ATTACKED.  71 

advocates  of  the  selection  theory  have  to  admit,  says  Wolff, 
that  they  face  a  serious  matter  here.  Weismann  *  is  quoted 
as  follows :  "Wenn  man  sich  die  Umwandlung  deshalb  in 
grosseren  Schritten  und  durch  Variationen  von  qualitativer 
Natur  geschehend  denkt,  so  wird  man  iiber  dieses  Hindernis 
nicht  wegkommen.  Ich  glaube  aber,  dass  man  von  den 
Variationen  grosseren  Betrages,  wie  sie  bei  domestizierten 
Tieren  und  Pflanzen  nicht  selten  vorkommen,  bei  den  Pro- 
zessen  der  Artumwandlung,  wie  sie  in  der  freien  Natur  vor 
sich  gehen,  vollstandig  abgesehen  hat,  dass  hier  tiberhaupt 
nicht  qualitative  sondern  nur  quantitative  Unterschiede  der 
Individuen  das  Material  der  Naturziichtung  bilden,  solche 
aber  sind  immer  vorhanden."  Wolff  holds  that  there  can 
simply  be  no  doubt  that  if  natural  selection  can  do  any 
modifying  at  all  it  has  at  most  to  limit  itself  solely  to  work 
possible  on  a  basis  of  quantitative  variation  of  already  ex- 
isting structures. 

Variation  also  of  whatever  kind  is  subject  to  Galton's  4  law 
of  regression.  This  is,  put  briefly,  that  the  young  of 
Galton's  law  parents  varying  from  the  mean  of  their  species 
of  regression,  or  race  tend  to  vary  also  in  the  same  direction 
but  less  so  than  the  parent,  so  that  the  mean  or  mode  among 
the  young  is  nearer  the  species  or  race  type  (mean  or  mode) 
than  the  parental  type  was.  Or  as  Morgan  8  has  stated  it : 
"The  facts  of  observation  show  that  when  a  new  variety  ap- 
pears its  descendants  are  more  likely,  on  the  average,  to 
produce  proportionately  more  individuals  that  show  the  same 
variation,  and  some  even  that  may  go  still  farther  in  the 
same  direction.  If  these  latter  are  chosen  to  be  the  parents 
of  the  next  generation,  then  once  more  the  offspring  may 
show  the  same  advance ;  but  little  by  little  the  advance  slows 
down,  until  before  long  it  may  cease  altogether.  Unless, 
then,  a  new  kind  of  variation  appears,  or  a  new  standard  of 
variation  develops  of  a  different  kind,  the  result  of  selection 
of  fluctuating  variations  has  reached  its  limit.  Our  experi- 


72  DARWINISM   TO-DAY. 

ence  seems,  therefore,  to  teach  us  that  selection  of  fluctuating- 
variations  leads  us  to  only  a  certain  point,  and  then  stops  in 
this  direction.  We  get  no  evidence  from  the  facts  in  favour 
of  the  view  that  the  process,  if  carried  on  for  a  long  time, 
could  ever  produce  such  great  changes,  or  the  kind  of 
changes,  as  those  seen  in  wild  animals  and  plants." 

There  is  something  inherent  in  the  make-up  of  the  organ- 
ism and  something  inevitably  incident  to  the  phenomena  of 
variation  which  prohibit,  even  in  the  most  favourable  cases, 
the  indefinite  movement  of  variation.  Johannsen,6  pro- 
fessor of  plant  physiology  in  the  University  of  Copenhagen, 
finds  that  beans  bred  in  pure  lines,  •/.  e.,  not  crossed,  conform 
perfectly  with  Galton's  law  of  regression.  And  Johannsen 
holds  that  this  regression  must  be  a  serious  brake  on  the 
species-modifying,  i.  e.,  species-forming,  activity  of  natural 
selection.  That  is,  while  the  species  mode  can  be  moved  in 
one  direction  or  another  by  pure  line  breeding  it  can  be  so 
moved  only  very  slowly.  And  this  same  law  of  regression 
will  tend  to  break  up  a  "mixed  population"  resulting  from 
crossed  and  miscellaneous  breeding  into  distinct  pure  lines  ; 
that  is,  each  independent  form-type  tends  to  be  constant,  not 
constantly  moving,  i.  e.,  transforming.  New  types  must 
arise  chiefly  then  through  (a)  the  crossing  of  races  or 
species  (=  hybridisation)  or  (b)  through  mutations. 

Delage  7  in  his  criticism  of  selection  makes  the  point  that 
because  the  causes  of  variation  are  more  feeble  than  the 
Dela  e'scriti-  causes  °^  fixity  (as  evidenced  by  the  massing  of 
cism  of  Deibceufs  variations  around  and  close  to  the  mean  or  mode, 
and  their  increasing  scarcity  as  they  recede  in 
any  direction  from  the  mode  (species  type)),  the  species 
tends  always  to  stand  still  rather  than  to  change.  If  in  the 
first  generation  a  thousandth  of  the  individuals  vary  in  the 
same  way,  in  the  second  generation  only  i-iooo  of  the 
thousandth  part  will  show  the  same  variation,  reasons 
Delage.  But,  as  pointed  out  in  chapter  vi  ("Darwinism  De- 


DARWINISM   ATTACKED.  73 

fended"),  this  criticism  was  long  ago  met  by  Delboeuf,  who 
claimed  to  show  mathematically  that,  however  feeble  may  be 
the  number  of  varying  individuals  compared  with  those 
non-varying,  the  number  of  the  varying  will  always  be 
increasing  and  will  finish  by  being  greater  than  that  of  the 
individuals  holding  to  the  type.  Delage  holds  "Delboeuf  s 
law"  to  be  false  as  regards  its  attempted  general  applica- 
tion to  the  selection  of  variation,  conceding  it  to  hold  true 
only  in  the  hypothetical  case  where  a  persistent  active  modi- 
fying cause  influences  for  some  reason  but  a  part  of  the 
individuals  of  a  species.  And  Delage  cannot  conceive  of  a 
cause  endowed  with  such  an  attribute. 

An  objection  that  has  been  often  made  to  the  natural 

selection  theory  may  be  put  in  the  following  general  form  : 

0  .    .  It  may  be  granted  that  selection  can  make  evolu- 

Selection  may      .         ; 

produce  evolution  tion,  i.  e.,  adaptive  change  or  progress,  but  this 
wil1  be  done  in  such  a  wa    as  to  leave  a  con- 


species  (discon-    tinuous   chain    or   series.     How    is    the   chain 

tinuous  series),      i       i         •    ,  •      ->       A          n  1 

broken  into  species  ?  Are  all  our  species  simply 
the  existent  ends  of  series  or  chains?  But  we  see  many 
chains  or  series  of  discontinuous  but  obviously  connected 
species.  Natural  selection  can  make  evolution  but  not 
species.  Darwin  himself  couched  this  objection  more  con- 
cisely as  follows  :  "Why,  if  species  have  descended  from 
other  species  by  fine  gradations,  do  we  not  everywhere  see 
innumerable  transitional  forms?  Why  is  not  all  nature  in 
confusion,  instead  of  the  species  being,  as  we  see  them,  well 
defined?" 

Professor  Morgan,  in  his  "Evolution  and  Adaptation," 
discusses  this  objection  in  the  following  paragraphs  (pp. 
129-131): 

"The  answer  that  Darwin  gives  [to  his  own  just  quoted 
query]  is,  that  by  competition  the  new  form  will  crowd  out 
its  own  less-improved  parent  form,  and  other  less-favoured 
forms.  But  is  this  a  sufficient  or  satisfactory  answer?  If 


74  DARWINISM   TO-DAY. 

we  recall  what  Darwin  has  said  on  the  advantage  that 
those  forms  will  have  in  which  a  great  number  of  new 
variations  appear  to  fit  them  to  the  great  diversity  of 
natural  conditions,  and  if  we  recall  the  gradations  that  exist 
in  external  conditions,  I  think  we  shall  find  that  Darwin's 
reply  fails  to  give  a  satisfactory  answer  to  the  question. 

"It  is  well  known,  and  Darwin  himself  has  commented  on 
it,  that  the  same  species  often  remains  constant  under  very 
diverse  external  conditions,  both  inorganic  and  organic. 
Hence  I  think  the  explanation  fails,  in  so  far  as  it  is  based 
on  the  accumulation  by  selection  of  small  individual  varia- 
tions that  are  supposed  to  give  the  individuals  some  slight 
advantage  under  each  set  of  external  conditions.  Darwin 
admits  that  'this  difficulty  for  a  long  time  quite  confounded 
me.  But  I  think  it  can  be  in  large  part  explained/  The 
first  explanation  that  is  offered  is  that  areas  now  continuous 
may  not  have  been  so  in  the  past.  This  may  be  true  in 
places,  but  the  great  continents  have  had  continuous  areas 
for  a  long  time,  and  Darwin  frankly  acknowledges  that  he 
'will  pass  over  this  way  of  explaining  the  difficulty/  The 
second  attempt  is  based  on  the  supposed  narrowness  of  the 
area,  where  two  species,  descended  from  a  common  parent, 
overlap.  In  this  region  the  change  is  often  very  abrupt, 
and  Darwin  adds : 

"  'To  those  who  look  at  climate  and  the  physical  condi- 
tions of  life  as  the  all-important  elements  of  distribution, 
these  facts  ought  to  cause  surprise,  as  climate  and  height 
or  depth  graduate  away  insensibly.  But  when  we  bear  in 
mind  that  almost  every  species,  even  in  its  metropolis,  would 
increase  immensely  in  numbers,  were  it  not  for  other  com- 
peting species;  that  nearly  all  either  prey  on  or  serve  as 
prey  for  others ;  in  short,  that  each  organic  being  is  either 
directly  or  indirectly  related  in  the  most  important  manner 
to  other  organic  beings, — we  see  that  the  range  of  the  in- 
habitants of  any  country  by  no  means  exclusively  depends 


DARWINISM   ATTACKED.  75 

on  insensibly  changing  physical  conditions,  but  in  a  large 
part  on  the  presence  of  other  species,  on  which  it  lives,  or 
by  which  it  is  destroyed,  or  with  which  it  comes  into  com- 
petition; and  as  these  species  are  already  defined  objects, 
not  blending  one  into  another  by  insensible  gradations,  the 
range  of  any  one  species,  depending  as  it  does  on  the  range 
of  others,  will  tend  to  be  sharply  defined/ 

"Here  we  have  a  petitio  principii.  The  sharp  definition  of 
species,  that  we  started  out  to  account  for,  is  explained  by 
the  sharp  definition  of  other  species ! 

"A  third  part  of  the  explanation  is  that,  owing  to  the 
relative  fewness  of  individuals  at  the  confines  of  the  range 
during  the  fluctuations  of  their  enemies,  or  of  their  prey, 
or  in  the  nature  of  the  seasons,  they  would  be  extremely 
liable  to  utter  extermination.  If  this  were  really  the  case, 
then  new  species  themselves  which,  on  the  theory,  are  at 
first  few  in  numbers  ought  to  be  exterminated.  On  the 
whole,  then,  it  does  not  appear  that  Darwin  has  been  very 
successful  in  his  attempt  to  meet  this  objection  to  the 
theory." 

A  rather  surprising  objection  is  that  of  Pfeffer,8   who 

contends  that  selection  cannot  be  the  cause  of  the  formation 

of  species,  for  if  it  were  real,  however  feeble 

Pfeffer'sobjeo-   .         ^  , 

tion  based  on  the  lts  effects,  it  would  transform  species  much 
slowness  of  spe-  more  rapidly  than  they  are  transformed;  and  in 

cies  change. 

order  to  transform  a  species  in  a  long  time  the 
protection  afforded  by  the  selection  of  small  additions  or 
modifications  is  so  feeble  as  to  be  illusory.  And  adequate 
protection  under  such  a  system  of  species  transformation 
is  imperative.  This  is  a  curious  argument,  for  it  has  always 
been  one  of  the  claims  of  the  mutationists  that  a  "hurry- 
up"  theory  is  needed  in  order  to  satisfy  the  familiar  objec- 
tion that  the  physicists'  estimate  of  the  actual  age  of  the 
world  is  too  low  to  admit  of  the  production  of  the  hosts  of 
kinds  of  ajiimals  and  plants  which  we  know  to  have  existed 


7<5  DARWINISM   TO-DAY. 

by  the  process  of  natural  selection.  But  Pfeffer,  who  is 
an  ingenious  debater,  makes  out  a  very  plausible  case  for  his 
contention. 

Of  the  many  special  questions  that  have  been  asked  of  the 
selectionists  two  may  be  mentioned,  simply  as  examples  illus- 
trative of  a  rather  formidable  category  of  objections  most 
of  which  are  concerned  with  certain  particular  phases  of 
evolution  or  groups  of  evolution  phenomena  rather  than 
with  the  whole  problem  of  species-forming.  Many  such 
special  objections  or  questions  touching  specific  cases  were 
taken  up  and  answered  by  Darwin  in  his  "Origin  of 
Species."  Morgan  has  recently  ("Evolution  and  Adapta- 
tion") gone  over  critically  many  of  these  special  objections 
and  Darwin's  answers  to  them,  and  pointed  out  clearly 
that  in  numerous  cases  Darwin  relied  for  his  answers  on 
evolution  factors  which  the  neo-Darwinians  have  attempted 
to  read  out  of  court.  In  many  tight  places  Darwin  availed 
himself  of  the  Lamarckian  factor  of  the  cumulation,  through 
inheritance,  of  the  effects  of  use  and  disuse,  or  of  other 
functional  stimuli  originating  either  in  internal  or  ex- 
trinsic conditions.  That  is,  Darwin,  while  constantly  trying 
to  rely,  and  whenever  possible  relying  on  natural  selection 
as  the  species-forming  and  adaptation-explaining  cause, 
never  hesitated,  when  it  seemed  necessary,  to  admit  the 
influence  and  effect  of  the  inheritance  of  acquired  characters 
or  the  influence  of  other,  to  him,  unknown  factors.  In 
most  cases  of  degeneration,  for  example,  he  adopted  a 
Lamarckian  explanation. 

The  question  of  how  sterility  between  species  could  have 

arisen  is  a  case  in  point.     "That  this  property  of  species  is 

useful  to  them  in  the  somewhat  unusual  sense 

explains/inter-  t^lat  ^  keeps  them  from  freely  mingling  with 

species  sterility    other  species  is  true,"  says  Morgan;  "but  this 

by  selection, 

would  be  a  rather  peculiar  kind  of  adaptation. 
If,  however,  it  be  claimed  that  this  property  is  useful  to 


DARWINISM   ATTACKED.  77 

species,  as  Darwin  himself  claims,  then,  as  he  also  points  out, 
it  is  a  useful  acquirement  that  cannot  have  arisen  through 
natural  selection.  It  is  not  difficult  to  show  why  this  must 
be  so.  If  two  varieties  were  to  some  extent  at  the  start 
less  fertile,  inter  se,  than  with  their  own  kind,  the  only  way 
in  which  they  could  become  more  infertile  through  selection 
would  be  by  selecting  those  individuals  in  each  generation 
that  are  still  more  infertile,  but  the  forms  of  this  sort  would, 
ex  hypothese,  become  less  numerous  than  the  descendants 
of  each  species  itself,  which  would,  therefore,  supplant  the 
less  fertile  ones."  Darwin  admits  that  this  situation  cannot 
apparently  be  explained  by  natural  selection,  and  simply 
says  that  to  him  it  appears  "that  the  sterility  both  of  first 
crosses  and  of  hybrids  is  simply  incidental  or  dependent  on 
unknown  differences  in  their  reproductive  systems." 

Wolff  9  has  urged  strongly  the  objection  that  natural  selec- 

tion does  not  explain  the  degeneration  or  atrophy  of  parts, 

at  least  not  large  or  nearly  complete  reduction. 

Objection  that 

selection  cannot   And   Weismann   and   other   selectionists    long 


conceded  that  some  sort  of  auxiliary  prin- 
generationof  ciple  was  necessary  to  explain  degeneration  on 
a  Darwinian  basis.  This  principle  was  supplied 
by  Weismann,  under  the  name  of  panmixia,  which  is,  simply, 
that  a  constantly  active  selection  is  necessary  not  only  for 
the  evolutionary  development  or  specialisation  of  an  organ 
but  as  well  for  its  retention  in  specialised  condition.10 
So.  that  an  organ  which  is  no  longer  used  and  is  therefore 
useless  comes  no  longer  under  the  supporting  influence  of 
selection  (on  the  basis  of  advantage)  and  must  consequently 
degenerate.  But,  as  Wolff  says,  it  seems  obvious  that  such 
an  influence  or  effect  of  the  cessation  of  selection  or  of 
panmixia  (so-called  by  Weismann  because  all  variations 
good  and  bad  alike  mix  -md  compensate  each  other)  can 
at  best  lead  to  degeneration  or  atrophy  only  when  the 
negative  or  reducing  variations  are  in  the  majority,  for  when 


78  DARWINISM   TO-DAY. 

this  is  not  the  case  the  average  of  the  survivors  cannot 
change.  Weismann  himself  has  in  recent  years  recognised 
the  inadequacy  of  panmixia  alone  to  explain  degenerative 
phenomena.  He  says:12  .  .  .  "In  most  retrogressive  pro- 
cesses active  selection  in  Darwin's  sense  plays  no  part, 
and  advocates  of  the  Lamarckian  principle,  as  above  re- 
marked, have  rightly  denied  that  active  selection,  that  is, 
the  selection  of  individuals  possessing  the  useless  organ  in 
its  most  reduced  state,  is  sufficient  to  explain  the  process  of 
degeneration.  I,  for  my  part,  have  never  assumed  this, 
and  have  on  this  very  account  enunciated  the  principle  of 
panmixia.  Now,  although  this,  as  I  have  still  no  reason 
for  doubting,  is  a  perfectly  correct  principle,  which  really 
does  have  an  essential  and  indispensable  share  in  the  process 
of  retrogression,  still  it  is  not  alone  sufficient  for  a  full  ex- 
planation of  the  phenomena.  My  opponents,  in  advancing 
this  objection,  were  right,  to  the  extent  indicated,  and  as 
I  expressly  acknowledge,  although  they  were  unable  to 
substitute  anything  positive  in  its  stead  or  to  render  my 
explanation  complete.  The  very  fact  of  the  cessation  of 
control  over  the  organ  is  sufficient  to  explain  its  degenera- 
tion, that  is,  its  deterioriation,  the  disharmony  of  its  parts, 
but  not  the  fact  which  actually  and  always  occurs  where  an 
organ  has  become  useless — viz.,  its  gradual  and  unceasing 
diminution  continuing  for  thousands  and  thousands  of  years 
and  culminating  in  its  final  and  absolute  effacement." 

To  supply  the  lack  in  the  present  neo-Darwinian  explana- 
tion of  retrogression  Weismann  calls  on  his  new  theory  of 
germinal  selection,  the  "rehabilitator  of  the  natural  selec- 
tion theory"  (for  an  account  of  this  theory  see  chapter  viii). 
But  Wolff  and  Morgan  and  others  have  shown  how  unsatis- 
factory and  inadequate  this  third  attempt  at  an  explanation 
is,  even  if  we  grant  the  actuality  of  germinal  selection,  a 
hypothesis  which  has  by  no  means  met  with  any  general 
acceptance  by  biologists. 


DARWINISM   ATTACKED.  79 

In  all  our  discussion  of  the  effectiveness  of  the  natural 
selection  theory  one  feature  of  it  has  so  far  not  been  ques- 
tioned. And  that  is  the  actual  selecting  power  when  the 
variations  or  differences  among  individuals  are  large  enough 
to  be  conceivably  of  real  advantage  or  disadvantage  to  the 
respective  organisms.  That  is  to  say,  we  have  not  brought 
into  question  the  alleged  rigour  of  the  struggle  for  existence 
upon  which  rigour  depends,  of  course,  the  selection  and  the 
survival  of  the  fittest.  The  very  phrases  "struggle  for  ex- 
istence" and  "survival  of  the  fittest"  presuppose  and  assume 
a  rigour  of  competition  and  a  life-and-death-determining 
value  of  the  variations  or  differences  that  are  fundamental 
features  of  the  natural  selection  theory.  Let  us,  however, 
not  hesitate  to  scrutinise  these  basic  assumptions  of  the 
Darwinians. 

What  of  the  actual  rigour  of  the  struggle  that  must  be 
presupposed  in  order  to  give  small  variations  a  life-and- 
death-determining  worth  ?  Does  it  exist  ?  Has 

Scrutiny  of  the 

claimed  extreme  it  been  observed?  Is  the  actual  (admitted) 
stfugglfandthe  production  of  thousands  or  millions  of  eggs 
consequent  per-  or  embryos  in  localities  capable  of  supporting 
but  tens  or  hundreds  of  individuals,  sufficient 
reason  for  deducing  an  endless,  searching,  utterly  rigorous 
competition  sufficient  to  give  the  slightest  variations 
a  weight  in  the  balances  determining  death  or  life? 
In  the  first  place,  this  tremendous  competition  must  be 
largely  over,  if  it  exists,  before  the  individuals  come  to 
maturity.  Especially  is  this  absolutely  true  of  all  species 
that  live  for  a  long  time  in  immature  stages  and  a  very  short 
time  in  the  adult  stage,  as  the  Mayflies  18  with  only  a  night- 
long adult  life.  Many  insects  of  complete  metamorphosis 
(i.  e.,  those  whose  adult  stage,  assumed  during  a  quiescent 
encased  pupal  stage,  is  very  different  from  their  larval 
stage)  which  have  very  elaborate  structural  specialisations  in 
the  adult  stage  have  had  their  fate  as  offspring-producing 


So  DARWINISM    TO-DAY. 

agents  decided  for  them  in  immature,  i.  e.,  egg,  larval,  or 
pupal,  life,  and  this  immature  life  is  in  most  cases  by  far 
the  larger  part  of  the  insect's  duration  of  existence. 

Henslow 14  sowed  together  the  same  quantity  of  two 
kinds  of  wheat  in  a  square  yard  of  ground.  The  young 
wheat  plants  that  came  up  were  many  times  as  many  as  the 
soil  could  support ;  the  passive  struggle  for  life  was  intense. 
In  the  end  twenty  heads  ripened  and  these  were  all  of  one 
of  the  two  kinds  sown.  The  experiment  was  repeated  in 
the  following  year  with  the  same  result.  In  the  struggle 
one  kind  of  wheat  had  a  distinct  advantage  over  the  other. 
But  this  selection  depended  wholly  on  special  characters  or 
strength  of  the  young  stages.  None  of  the  adult  characters 
cut  any  figure  in  this  selection,  which  was  decided  before 
ever  the  plants  came  to  maturity.  And  this  is  true,  it  seems 
to  me,  of  most  of  struggle  and  selection. 

It  is  not  in  the  adult  state  that  the  oppressive  abundance 
exists :  in  the  forest  to-day  are  about  as  many  crows  as  last 
year ;  in  the  meadows  as  many  yellow  butterflies  as  in  sum- 
mers by.  The  eggs  and  the  young  are  the  stages  which 
figure  in  mortality  tables.  They  need  the  variations  and 
adaptations ;  the  pressure  is  largely  gone  before  maturity  is 
reached.  However,  the  adaptations  of  the  fully-developed 
body,  in  structure  and  function,  certainly  do  not  fall  behind 
those  of  the  embryonic  and  immature  stages.  Indeed  they 
obviously  are  more  complex  and  perfected. 

But  after  all  what  determines  just  what  millions  of  trout's 
Indiscriminate  eggs  sna^  be  destroyed  and  what  thousands 
death,  s}iau  hatch  small  fry  ?  Many  a  sharp-eyed  trout 

fisherman,  many  a  keen-witted  nature  observer,  many  a 
trained  biologist  will  answer:  Chiefly  chance,  the  luck  of 
position,  the  good  fortune  of  not  being  devoured  by  the 
roaming  things  that  paddle  or  crawl  in  the  upper  reaches  of 
trout  streams.  What  shall  decide  when  the  big  whale  opens 
his  mouth  in  the  midst  of  a  shoal  of  myriads  of  tiny 


DARWINISM   ATTACKED.  81 

Copepods  floating  in  the  pelagic  waters  of  the  Aleutian  seas, 
what  Copepods  shall  disappear  forever?  Mainly,  we  may 
say,  the  chance  of  position.  A  bit  more  or  less  of  size,  or 
strength,  or  redness,  or  yellowness,  or  irritability  or  what 
not  of  form  and  function  is  going  to  avail  little  when  the 
water  rushes  into  the  yawning  throat.  Now  this  chance 
and  this  luck  are  the  luck  and  chance  of  the  law  of  prob- 
abilities; that  is,  luck  and  chance  capable  of  being  mathe- 
matically determined.  Given  so  much  ocean,  with  so  many 
whales  swimming  about  in  such  and  such  curves  at  such  and 
such  rates  and  opening  and  closing  their  mouths  inter- 
mittently at  such  and  such  intervals,  and  just  so  many 
shoals  of  so  many  million  Copepods,  these  shoals  at  such  and 
such  distances  apart,  and  any  mathematical  friend  will 
reckon  for  you  the  chances  any  one  Copepod  individual  has 
at  any  given  moment  of  being  swallowed.  But  Darwinian 
variations  in  the  Copepod  body  will  be  represented  by  no 
function  in  the  mathematician's  formula.  When  the  scores 
of  little  streams  dry  in  California  every  summer,  what  deter- 
mines whether  millions  of  Californian  water-insects  of 
scores  of  kinds  shall  die  in  July  or  not?  Mainly  life  or 
death  is  determined  for  them  by  their  good  or  ill  luck  in 
being  in  one  of  the  few  streams  that  do  not  dry  up,  or  in 
one  of  the  many  that  do  dry.  Kelsey  Creek  runs  into 
Clear  Lake,  in  northern  California ;  it  is  usually  ever-living, 
but  some  summers  it  suddenly  dries  up.  Fish  play  back  and 
forth  between  this  stream  and  the  lake;  at  the  time  of  the 
sudden  drying  a  few  hundreds  of  thousands  out  of  many 
hundreds  of  thousands  that  habitually  live  in  the  stream  and 
adjacent  lake  waters  find  themselves  one  awful  day  gasping 
painfully  for  water  to  wet  their  drying  gills.  They  gasp  a 
short  while  and  then  die.  Did  they  all  have  the  same  num- 
ber of  scales,  the  same  shape  and  size  of  body,  the  same 
tinges  of  fleeting  colour  ?  No,  they  represented  most  of  the 
possible  gamut  of  Darwinian  variation  for  their  particular 


82  DARWINISM   TO-DAY. 

species.  But  they  were  dead  all  together,  by  the  ill-chance 
of  position.  In  Lagunita,  a  small  artificial  lake  on  the 
campus  of  Stanford  University,  water  pours  in  from  two  or 
three  rivulets  during  the  rainy  season  so  as  to  fill  it  and 
make  it  an  abiding  place  for  many  aquatic  organisms  that 
'swim  in  or  are  washed  in  through  the  dikes.  And  thou- 
sands of  little  fishes  and  water  beetles  and  dragon-fly 
nymphs  and  the  like  live  contentedly  there  for  seven  or  eight 
months.  But  with  the  rainless  summer  months  come  swift 
evaporation  and  steady  leakage,  and  by  September  all  the 
thousands  of  little  fishes  and  insects  lie  dying  there  together 
in  the  last  few  puddles.  It  is  the  hard  luck  of  a  fatal  chance 
against  which  all  the  variations  in  colour,  in  size,  in  scales, 
in  spines,  and  what  not  are  as  one  as  far  as  helping  or  sav- 
ing any  of  the  gasping  possessors  is  concerned. 

One  might  go  on  tiresomely  but  one  does  not  need  to  point 
the  moral  of  these  tales.  Wolff  15  has  clearly  fancied  how 
the  fate  of  millions  of  tapeworms  may  hang  on  the  recep- 
tion in  the  German  Reichstag  of  a  clever  speech  for  or 
against  meat  laws.  To  go  so  far  isn't  necessary :  the  very 
life-history  of  the  tapeworm  and  of  hundreds  of  similarly- 
lived  vermian  parasites  shows  to  what  nearly  absolute  de- 
gree chance  rules  their  fate,  and  how  utterly  insignificant 
a  part  in  it  miscellaneous  individual  variation  can  possibly 
play. 

But  aside  from  the  part  that  what  we  may  call  fortune  18 
of  position  plays  in  determining  life  or  death  among  indi- 
viduals, what  of  the  actual  rigour  of  the  strug- 
£le  in  those  cases  where  death  does  not  come 
to  thousands  at  a  moment; — in  the  whale's 
mouth,  by  catastrophe  of  flood  or  drouth,  or  by  the  elephant's 
tread  on  the  ant-hill?  To  this  question  of  the  rigour  of 
intra-specific  struggle  I  have  given  some  personal  attention 
in  insect  life,  and  while  to  detail  observations  here  would 
be  impossible,  I  may  say  baldly  that  no  such  rigour  of  in- 


DARWINISM   ATTACKED.  83 

dividual  selection  based  on  variation  17  in  colour,  in  pattern, 
in  venation  and  other  wing  characters,  in  hairs  and  in 
numerous  other  structural  characters,  as  demanded  by  the 
needs  of  the  selection  theory,  is  to  be  detected.  I  find 
just  as  much  variation  represented  in  series  of  mature 
individuals  collected  miscellaneously  after  having  lived  for 
more  or  less  time  a  free  life  exposed  to  all  the  dangers  of 
this  life,  exposed,  that  is,  to  the  rigour  of  the  individual 
struggle  for  existence,  as  among  series  of  similar  extent  of 
individuals  of  the  same  species  collected  just  at  the  time  of 
reaching  maturity  but  before  enjoying  any  opportunity  to 
be  weeded  out  (on  a  basis  of  disadvantageous  variation) 
by  the  rigour  of  the  life-struggle.  Just  as  many  varying 
individuals,  with  variations  of  just  as  much  extent  and  va- 
riety, were  found  in  series  exposed  to  the  struggle,  in  which 
these  variations  are  presumably  capable  of  saving  or  losing 
life,  as  among  series  not  yet  exposed;  in  other  words,  just 
as  much  variation  exists  after  enduring  the  selective  rigour 
of  the  struggle  as  existed  on  the  day  when  the  insects  are 
first  exposed  to  it. 

Conn  18    expresses   his  belief   concerning  destruction  by 
chance  and  the  rigour  of  the  struggle  as  follows : 
n     ,  ,.  "Indiscriminate     destruction     occurs     con- 

Uonn  s  discus- 
sion of  the  chances  stantly,  and  certainly  influences  the  problem  of 
ofdeath,  survival.     Of  the  hundreds  of  individuals  that 

are  produced  where  few  can  live,  many  are  destroyed  in- 
discriminately, independent  of  the  principle  of  survival  of 
the  fittest,  and  of  these  that  are  thus  killed  doubtless  some 
are  superior  to  those  that  survive.  This  principle  of  indis- 
criminate elimination  does  not  in  the  slightest  deny  the 
force  of  the  principle  of  survival  of  the  fittest,  but  only  indi- 
cates that  its  action  is  not  absolutely  rigid.  The  fittest  do 
not  always  survive,  for  many  of  them  are  destroyed. 

"On  the  other  hand  the.  least  fit  do  not  always  perish. 
Whether  an  individual  shall  live  or  die  in  the  struggle  is 


84  DARWINISM   TO-DAY. 

largely  a  matter  of  accident.  Many  a  well-equipped  indi- 
vidual will  die,  while  many  another,  even  though  handi- 
capped by  decidedly  unfavourable  characters,  will  continue 
to  live  and  produce  offspring  because  of  some  specially 
favourable  conditions.  Nothing  could  seem  to  be  more 
decidedly  disadvantageous  than  a  broken  leg,  and,  if  the 
principle  of  elimination  of  the  unfit  were  rigid,  broken-legged 
individuals  should  be  speedily  destroyed.  But  it  is  quite 
common  to  find  animals  with  broken  legs  or  arms  which 
yet  succeed  in  living  perfectly  well.  They  have  repaired 
their  broken  members  by  processes  of  bone  growth,  and  have 
been  able  to  carry  on  their  part  in  the  struggle  for  life  and 
survive  competition.  I  have  found  a  frog  with  the  whole 
of  both  feet  bitten  off,  and  yet  with  the  wounds  healed,  the 
animal  living  without  feet,  and  hence  hardly  able  to  swim, 
but  side  by  side  in  competition  with  other  well-developed 
animals.  I  have  found  a  clam  that  in  its  young  condition 
had  received  a  severe  rent  in  one  gill,  through  which,  by 
some  twist  the  body  had  been  thrust,  giving  rise  to  the 
extraordinary  condition  of  three  gills  on  one  side  of  the 
body  and  one  on  the  other,  a  truly  monstrous  abnormity. 
But  this  clam  had  lived  to  maturity  and  produced  eggs  in 
quantities  equal  to  any  other  clam. 

"Now  such  instances  simply  show  the  complexity  of  the 
conditions  which  determine  survival.  They  indicate  that 
these  animals  were  favoured  in  some  respects  sufficiently  to 
counteract  the  disadvantage  of  their  mutilations.  But  the 
fact  that  so  many  instances  are  found  does  show  that  single 
characters  do  not  always  determine  survival  or  elimination. 
The  question  whether  an  individual  survive  is  dependent 
upon  many  factors,  of  which  utility  of  various  organs  may 
be  one  and  accident  another.  What  would  seem  more  sure 
from  a  logical  standpoint,  than  that,  in  the  intense  struggle 
for  life  due  to  numerous  individuals  seeking  for  food,  a 
frog  who  was  unable  to  swim  because  of  the  loss  of  his 


DARWINISM   ATTACKED.  85 

feet  would  be  sure  to  be  a  loser?  Even  if  the  inflammation 
caused  by  the  wound  did  not  destroy  him,  it  would  seem 
impossible  for  the  animal  to  obtain  his  share  of  food.  Of 
course,  a  footless  race  would  be  eliminated  in  a  compara- 
tively short  time,  but  the  survival  of  so  many  mutilated 
individuals  shows  that  selection  is  not  so  rigid  as  to  eliminate 
all  unfit  individuals,  even  though  their  disadvantage  be  very 
great. 

"If  a  very  disadvantageous  character  may  thus  fail  to  pro- 
duce destruction  it  must  be  still  more  true  that  a  favour- 
able character,  occurring  in  a  single  individual,  has  really 
little  chance  for  survival.  The  individual  possessing  it  will 
have  to  compete  with  accident,  with  indiscriminate  slaughter, 
and  with  other  conditions  which  we  bave  just  seen  may  be 
sufficient  to  preserve  even  a  broken-legged  individual. 
Nothing  can  seem  more  evident  than  that  the  web  of  the 
foot  and  the  muscles  of  the  legs  are  of  use  in  swimming, 
and  have  therefore  been  developed  by  the  preserving  influ- 
ence of  natural  selection.  If  anything  is  of  selective  value, 
these  characters  certainly  are.  But  when  we  find  that  a 
frog  with  no  feet  can  survive  the  struggle  for  existence,  it 
is  evidently  difficult  to  believe  that  single  variations,  either  of 
use  or  disadvantage,  will  have  any  special  likelihood  of  sur- 
viving at  the  expense  of  other  members  of  the  race,  so  as 
eventually  to  replace  all  others.  But  only  thus  can  they 
be  'seized  upon  by  natural  selection  and  preserved.'  " 

There  are  two  important  objections  to  the  natural  selec- 
tion theory  based  on  the  relations  of  this  theory  with  the 

_       .    .       two    other    selection    theories,    namely    sexual 

Natural  selec-  J 

tion  needs  the      selection  and  artificial  selection.     Wolff  19  has 
made  the  criticism  that  natural  selection  must 


theory,  which  is  be   supported   by   the   sexual    selection   theory 

in  order  to  stand.     It  makes  no  pretension  of 

explaining  those  extraordinary  secondary  sexual  characters 

such  as  ornamentation,  songs,  dances,  odours,  etc.,  which 


S6 


DARWINISM   TO-DAY. 


not  only  are  of  no  conceivable  utility  in  the  struggle  for 
existence  but  are  in  many  cases  of  obvious  disadvantage. 
It  relies  wholly  on  sexual  selection  to  explain  them,  and 
yet  in  Wolff's  eyes,  and  indeed  in  the  eyes  of  most  biologists, 
sexual  selection  is  practically  discredited.  It  certainly  can- 
not explain  some  or  many  of  these  characters.  (See  account 
of  the  sexual  selection  theory  and  the  criticisms  of  it  in 
the  next  chapter.)  Therefore,  say  Wolff  and  other  anti- 
Darwinians,  natural  selection  is  undermined  in  just  so  far 
as  it  relies  on  the  sexual  selection  theory  to  sustain  it. 

The  other  objection  is  that  the  natural  selection  theory 
rests  altogether  too  largely  on  an  unwarranted  analogy  with 
Natural  selec-  the  phenomena  of  artiScial  selection.  Plate  zo 
tion  rests  too  nas  graphically  expressed  the  contrast  between 
analogy  with  arti- the  facts  and  processes  of  the  two  kinds  of 
ficial  selection,  seiectiOn  in  the  following  double-column  table  : 


ARTIFICIAL   SELECTION. 

(1)  rests  on  the  wish  (Willen) 
and  intelligence  of  the  breeder, 
except  in  a  certain  few  cases  of 
"unintentional    breeding"     (See 

Darwin,  "Origin  of  Species.") 

(2)  selects     exceptional,     most 
widely      divergent      characters, 
which    appear    only    in    a    few 
individuals. 

(3)  complete     isolation     (pure 
breeding)    of  the   selected  indi- 
viduals. 

(4)  often  leads  to  exaggerated 
development  and  to  a  sickly  dis- 
position, so  that  the  whole  con- 
stitution suffers. 

(5)  leads  comparatively  rapidly 
to  new  forms. 


(6)      The      artificially-produced 


NATURAL   SELECTION. 

(i)  rests  on  the  unvolitional 
and  unreasoning  resultant  of 
natural  forces. 


(2)  is  a  selection  of  slight  dif- 
ferences,    appearing     simultane- 
ously in  many  individuals. 

(3)  pure  breeding  is  often  very 
difficult    through    the    possibility 
of    crossing    with    the    parental 
type. 

(4)  effects    no    injury    to    the 
whole    constitution,    but    on    the 
contrary     a     strengthening     and 
bettering  of  it. 

(5)  The  modification  of  species 
is    effected,    presumably    almost 
always,    very    slowly,    for    if    it 
were    otherwise    the    appearance 
of  new   species   would  be  often 
observed. 

(6)  The    natural    races    (varie- 


DARWINISM    ATTACKED.  87 

races  are   unstable;   they  revert  ties)    are    stable;    they    do    not 

easily   to   the    ancestral   type    if  revert    if    the    outer    conditions 

allowed  to  run  wild;  this  is  so  (environment)  remain  constant; 

probably  because  of  their  recent  this  is  so  probably  because  they 

origin.  are   more   firmly  established   by 

reason  of  greater  age. 

(7)      The      artificially-produced  (7)     Natural    varieties    do    not 

races    of   the    same    species    are  cross     in     nature,     either     with 

in    most    cases    fertile    among  each  other  or  with  the  ancestral 

themselves.  type. 

The  most  important  contrast  between  the  two  kinds  of 
selection  lies,  in  my  eyes  at  least,  in  the  results  obtained  in 
the  character  of  the  new  forms.  As  Morgan  21  well  says, 
"we  should  not  lose  sight  of  the  fact  that  even  after  the  most 
rigorous  selective  process  has  been  brought  to  bear  on 
organisms,  namely,  by  isolation  under  domestication,  we  do 
not  apparently  find  ourselves  gradually  approaching  nearer 
and  nearer  to  the  formation  of  new  species,  but  we  find,  on 
the  contrary,  that  we  have  produced  something  quite  differ- 
ent. In  the  light  of  this  truth,  the  relation  between  the  two 
selective  theories  may  appear  quite  different  from  the  inter- 
pretation that  Darwin  gives  of  it.  We  may  well  doubt 
whether  nature  does  select  so  much  better  than  does  man, 
and  whether  she  has  ever  made  new  species  in  this  way." 

De  Vries  expresses  very  positively  his  belief  that  no  artifi- 
cial races  are  fixed  and  constant  forms,  in  the  sense  that 
natural  varieties  are.  And  this  difference  he  believes  to  rest 
on  the  radically  different  method  23  of  origin  of  the  two 
kinds  of  forms;  the  domestic  ones  through  carefully  main- 
tained selection;  the  natural  ones  through  definitive  imme- 
diately fixed  and  enduring  mutations. 

If  one  stops  to  recall  his  own  familiar  knowledge  of  the 
cultivated  plants  23  and  will  roughly  classify  the  cultivated 
fruits  and  vegetables  and  ornamental  plants  with  which  he  is 
acquainted  into  two  categories  depending  upon  the  mode  of 
reproduction,  that  is  whether  by  division  or  by  seeds,  one 
will  be  struck  by  the  great  preponderance  of  the  first  of  the 


88  DARWINISM   TO-DAY. 

two  categories, — the  category,  namely,  of  cultivated  plant 
races  which  are  reproduced  practically  exclusively  by 
division  (i.  e.,  by  cuttings,  roots,  scions,  buds,  etc.).  The 
reason  for  relying  upon  this  kind  of  reproduction  is,  in 
nearly  every  case,  that  these  races  do  not  breed  true  to  seed, 
i.  e.,  the  races  are  not  fixed,  are  unstable.  And  even  among 
those  races  which  we  are  accustomed  to  allow  to  reproduce 
by  seed  how  necessary  it  is  to  maintain  the  unusual  environ- 
ment, the  exaggerated  excellence  of  conditions  of  food 
supply,  humidity,  protection  from  natural  enemies,  etc.,  if  we 
are  to  be  successful  in  maintaining  the  parental  characters  of 
the  plant.  Let  a  few  individuals  escape  from  the  hothouse 
or  fertilised  and  sprinkled  garden  and  see  how  soon,  if  they 
can  persist  at  all,  they  lose  their  characters  of  amelioration, 
and  become  most  pitifully  unadorned. 

In  Pfeffer's  24  eyes  the  fundamental  difference  between 
the  two  selection  processes  rests  on  the  fact  that  the  breeder 
or  plant  ameliorator  selects  his  individuals  (the  "to  be 
saved")  on  the  basis  of  the  character  or  condition  of  single 
characteristics,  while  in  nature  survival  is  not  determined 
by  such  conditions,  but  on  a  basis  of  total  or  all-around  fitness 
or  advantage.  'The  moment,"  says  Pfeffer,  "that  one  be- 
lieves one's  self  to  be  able  to  place  in  parallel,  simply  and 
directly  and  in  general,  the  activity  of  the  breeder  and  the 
activity  of  the  struggle  for  existence,  and  from  this  false 
generalisation  deductively  to  compare  the  selective  work  of 
the  breeder  based  on  definitive  special  characters  with  the 
automatic  selective  work  of  nature  based  on  similar  specific 
characteristics,  that  moment  one  enters  the  camp  of  the 
teleologists,  whether  he  is  doing  it  knowingly  and  will- 
ingly, or  not.  In  short  it  is  a  logical  fallacy  when  one  as- 
sumes to  substitute  for  the  selective  action  of  the  breeder  a 
mechanically-working  natural  selection.  Only  in  a  single 
kind  of  case  has  this  position  any  justification,  and  this  not 
on  account  of  logical  correctness  but  on  account  of  the  pecu- 


DARWINISM   ATTACKED.  89 

liar  identity  of  the  circumstances.  And  this  is  when  a  single 
definitive  characteristic  is  so  all-important  and  dominant  in 
the  life  of  a  race  or  species  that  its  presence  really  has  a 
life-and-death-determining  value  in  the  struggle  for  exist- 
ence ;  in  this  case  the  killing  out  of  all  the  individuals  not 
provided  with  this  specific  character  has  the  same  re- 
sult as  an  actual  selection  of  the  possessors  of  this  char- 
acter. The  farther,  however,  the  actual  circumstances  differ 
from  this  case,  in  so  far  as  a  number  of  characteristics,  and 
not  a  single  one,  determines  the  outcome  of  survival,  by  just 
so  much  less  can  the  Darwinian  explanation  be  made  to 
cover  the  situation." 

De  Vries  sums  up  a  full  and  careful  discussion 25  of 
natural  as  compared  with  artificial  selection  as  follows :  "In 
conclusion,  summing  up  all  our  arguments  we  may  state  that 
there  is  a  broad  analogy  between  breeding-selection  in  the 
widest  sense  of  the  word,  including  variety-testing,  race- 
improvement,  and  the  trial  of  the  breeding  ability  on  one 
side,  and  natural  selection  on  the  other.  This  analogy,  how- 
ever, points  to  the  importance  of  the  selection  between  ele- 
mentary species,  and  the  very  subordinate  role  of  intra-specific 
selection  in  nature.  It  strongly  supports  our  view  of  the 
origin  of  species  by  mutation  instead  of  continuous  selec- 
tion. Or  to  put  it  in  the  terms  chosen  lately  by  Mr.  Arthur 
Harris  in  a  friendly  criticism  of  my  views  :  'Natural  selection 
may  explain  the  survival  of  the  fittest,  but  it  cannot  explain 
the  arrival  of  the  fittest.' " 

Finally  I  desire  to  add  an  objection  that  has  real  weight 

with  me,  whatever  may  be  the  personal  attitude  of  other 

An  increasing    naturalists  or  students  to  it.     And  that  is,  that 

nnmberofwork-  -  .  ,  .  t  . 

ing  biologists  a  constantly  increasing  number  of  working 
unsatisfied  with  biologists  find  themselves,  on  a  basis  of  their 

the  selection  .         .  . 

theories,  cumulative  individual  observation  and  experi- 

ence and  thought,  unsatisfied  with  the  explanation  of  adapta- 
tion and  species-forming  offered  by  the  selection  theories. 


90  DARWINISM   TO-DAY. 

Men  using,  or  rather,  testing,  these  theories  every  day  in 
their  work  in  field  and  laboratory,  find  selection  insufficient 
to  explain  the  conditions  that  their  observation  and  experi- 
ments reveal  to  them.  These  men  are  students  in  all  the 
different  lines  of  biological  work;  they  are  zoologists,  bota- 
nists, palaeontologists;  they  are  students  of  anatomy,  physi- 
ology, oecology,  and  taxomony  (classification)  ;  they  are 
embryologists,  pathologists,  animal  and  plant  breeders. 
From  all  these  lines  of  work  come  increasing  complaints; 
selection  cannot  explain  for  me  what  I  see  to  exist.  From 
some  the  cry  is  more  bitter :  selection  is  a  delusion  and  false 
guide;  I  reject  it  utterly.  For  me,  I  repeat,  this  is  an 
objection  of  much  significance  and  importance.  Just  as 
modern  chemistry  seems  to  be  finding  its  long  useful  atomic 
theory  now  a  restraint  and  a  hindrance  in  understanding  the 
wonderful  new  facts  that  have  followed  the  pushing  out  of 
investigation  into  the  rich  fields  of  physical  chemistry,  so 
the  biological  experimentalists,  the  students  of  variation  and 
heredity,  of  life  mechanics,  of  physico-chemical  biology, 
are  finding  the  rigid  theory  of  selection's  control  of  all 
processes  and  phenomena  a  rack  on  which  they  will  no 
longer  be  bound. 

Coupled  with  the  significance  of  this  general  objection  to 
the  reign  of  the  selection  theory — a  general  objection  that 

the  selectionists  will  say  is  simply  the  objection 
The  concessions   ,  J  .    J  J 

«f  the  selection-    that  the  selection  theory  is  objected  to — is  the 

18tSl  added  significance  of  the  concessions  in  the  way 

of  supporting  theories  that  the  neo-Darwinians  have  made 
to  the  general  increase  and  sharpness  of  scientific  criticism 
of  selection ;  conspicuous  examples  are  Roux's  theory  of  the 
battle  of  the  parts,  and  Weismann's  theory  of  germinal 
selection.  This  latter  is  no  less  than  a  neo-Darwinian  ex- 
planation of  how  determinate  variation,  that  is  ortho- 
genesis, may  be  explained  non-teleologically.  Which  is 
practically  to  rob  natural  selection  of  all  influence  in  the 


DARWINISM   ATTACKED.  91 

primary  determination  of  lines  of  descent.  But  to  these 
supporting  and  concessionary  theories  we  shall  come  in 
a  later  chapter. 

To  show  how  definitive  and  positive  an  anti-Darwinian 
position  is  taken  by  some  biologists  I  shall  quote  some  para- 
Zorschinsk  's   feraPns  from  an  interesting  short  paper  by  Kor- 
radical  anti-se-     schinsky,28  a  Russian  botanist  whose  formula- 
lection  position,    t.on  of  the  theory  of  species_forming  by  hetero. 

genesis  preceded  that  of  de  Vries  by  two  years.  In  this 
paper  (which  is  a  vorl'dufige  Mitteilung  published  in  Ger- 
man preliminary  to  the  issuance,  in  the  publications  of  the 
Royal  Academy  of  Sciences  of  St.  Petersburg,  of  a  larger, 
more  detailed  paper)  Korschinsky  arranges  in  parallel 
columns  the  various  corresponding  or  contrasting  items  of 
the  selection  theory  compared  with  the  heterogenesis  theory 
of  the  author  himself  (for  this  full  table  see  chapter  xi). 
From  this  table  I  quote  only  the  following  statements  to 
show  how  differently  from  the  Darwinian  view  the  probable 
effects  of  the  struggle  for  existence  may  appear  to  another 
naturalist  and  to  what  radically  anti-Darwinian  conclusions 
a  man  may  come  who  interprets  the  effects  of  selection  in 
this  way : 

"The  origin  of  new  forms  can  only  occur  under  condi- 
tions favourable  for  them,  and  the  more  favourable  such 
conditions  are,  that  is,  the  less  severe  the  struggle  for  ex- 
istence is,  the  more  energetic  is  their  development.  Under 
severe  external  conditions  new  forms  do  not  arise;  or  if  they 
appear  they  are  extinguished. 

'The  struggle  for  existence,  and  the  selection  which  goes 
hand  in  hand  with  it,  compose  a  factor  which  restricts  new- 
appearing  forms  and  restrains  wider  variations,  and  which  is 
in  no  way  favourable  to  the  production  of  new  forms.  It 
is  indeed  an  inimical  factor  in  evolution. 

"Were  there  no  struggle  for  existence,  then  there  would 
be  no  extinguishing  of  arising  or  already  arisen  forms.  The 


92  DARWINISM   TO-DAY. 

organic  world  could  then  develop  into  a  mighty  tree,  whose 
branches  could  all  remain  in  blooming  condition,  so  that 
the  now  isolated  extremest  species  would  be  united  with  all 
others  through  gradatory  forms. 

"The  adaptation  resulting  from  the  effects  of  the  struggle 
for  existence  is  absolutely  not  identical  with  advance,  for 
higher-standing,  more  complex  forms  are  by  no  means 
always  better  adapted  to  outer  conditions  than  the  lower 
ones.  The  evolution  [used  here  by  the  author  as  synony- 
mous with  advance  or  progressive  complexity]  of  organisms 
cannot  be  explained  in  a  purely  mechanical  way.  In  order 
to  explain  the  origin  of  higher  forms  from  lower  it  is  neces- 
sary to  postulate  in  the  organisms  a  special  tendency  to  ad- 
vance which  is  nearly  related  to  or  identical  with  the 
tendency  to  vary,  which  tendency  compels  the  organisms 
to  advance  so  far  as  the  outer  conditions  permit." 

These  declarations  sound  strange  and  perhaps  almost 
absurd  in  the  ears  of  one  accustomed  for  years  to 
hear  only  the  Darwinian  interpretation  of  the  effects  of  the 
struggle  for  existence  and  natural  selection.  But  taken 
up  one  by  one,  as  they  are  by  Korschinsky,  and  developed 
and  explained,  they  begin  to  have  a  kind  of  plausibility, 
an  appeal  to  our  reason,  of  much  that  sort  which  the  Dar- 
winian interpretation  has  and  makes.  After  all  the  Darwin- 
ian interpretation  is  proved  only  in  so  far  as  it  possesses  a 
high  degree  of  plausibility  and  makes  a  convincing  appeal 
to  our  reason.  Of  exact  proof,  in  the  nature  of  observed 
fact  or  result  of  experiment,  or  of  mathematical  demonstra- 
tion, there  is  little  in  the  case  either  of  the  Darwinian  or 
the  Korschinskian  interpretation. 

Those  other  biologists  27  who,  like  Korschinsky,  take  the 
extreme  and  positive  stand  that  the  struggle  and  selection 
are  not  factors  in  evolution,  or  if  factors  are  really  hinder- 
ing and  opposing  ones,  constitute,  however,  by  far  the 
smaller  body  in  the  ranks  of  the  anti-Darwinian  critics  when 


DARWINISM   ATTACKED.  93 

compared  with  those  whose  arraignment  of  selection  is 
chiefly  a  protest  against  its  assumption  of  altogether  an 
undue  share  of  influence  in  species-forming,  and  whose 
principal  attempt  is  to  reduce  selection  to  a  secondary  place 
among  evolutionary  factors,  giving  first  place  to  that  influ- 
ence or  those  influences  which  determine  the  character  and 
direction  of  variation.  Still  the  totally  anti-Darwinian 
critics  are  not  few,  and  are  not  without  ingenuity  and 
capacity  in  debate. 

But  better  justified  by  what  we  know  to-day  and  far  saner 
in  their  estimate  of  the  Darwinian  factors  are  such  critics 
as  Delage  and  Morgan.  "The  conclusion  of 
tnis  criticism,"  says  Delage,28  at  the  end  of  a 
detailed  critical  discussion  of  the  "true  role  of 
selection,"  "is  that  selection  is  powerless  to  form  species. 
Its  role,  however,  is  not  mil,  but  it  is  limited  to  the  sup- 
pression of  variations  radically  bad,  and  to  the  maintaining 
of  the  species  in  its  normal  character.  Far  from  being  an 
instrument  for  the  evolution  of  species  it  guarantees  their 
fixity."  And  elsewhere  he  says :  "Species  come  from  fixed 
variations.  The  formation  of  species  is  due  ordinarily  to 
general  variation  [a  conception  of  change  much  like  that  of 
de  Vries's  mutations  and  sudden  fixed  origin  of  elementary 
species],  very  rarely  to  strong  individual  variation  [sports  or 
discontinuous  variations],  and  never  to  weak  individual 
variation  [fluctuating  or  Darwinian  variation]. 

Morgan  29  in  a  recent  popular  essay  in  which  he  takes  a 
strong  stand  against  natural  selection  as  a  species-forming 
Morgan's  ad-  ^actor  and  in  favour  of  "definite  variations" 
verse  criticism  of  (de  Vriesian  mutations)  concludes  as  follows: 
ing  vPalne  of s™  "I*1  tne  preceding  pages  I  have  tried  to  bring 
lection.  jn|-o  contrast  the  point  of  view  of  the 

Darwinian  school  and  the  newer  conception  of  the  sur- 
vival of  elementary  species.  I  have  tried  to  show  what 
.selection  has  meant  to  the  selectionists.  They  have 


94  DARWINISM   TO-DAY. 

never  hesitated  to  take  each  particular  character  of  an 
animal  or  plant,  and  dress  it  up  in  more  perfect  gar- 
ments, while  the  body  of  the  species,  if  I  may  so  speak, 
has  been  left  as  it  was  before.  There  has  been  a  con- 
tinual tampering  with  the  characters  of  the  organism  with 
the  laudable  intention  of  doing  with  them  that  which  na- 
ture herself  seems  unable  to  do,  namely,  to  dissociate  them 
from  the  rest  of  the  organisation  and  perfect  them  in  this 
way  or  in  that.  It  is  this  meddling  with  the  fluctuating 
characters  of  the  species  that  has  been  the  characteristic 
procedure  of  the  Darwinians,  in  their  attempt  to  show  how 
new  species  have  been  created.  In  contrast  to  this  method, 
the  theory  of  the  survival  of  species  assumes  that  a  form 
once  made  does  not  have  its  individual  parts  later  disso- 
ciated and  adjusted  to  better  fit  the  external  needs  of  the 
species.  Such  a  new  form  can  change  only  by  becoming 
again  a  new  species  with  a  new  combination  of  characters ; 
some  of  which  may  be  more  developed  in  one  direction  than 
before,  others  less,  etc. 

"New  forms  on  the  Darwinian  theory  are  supposed  to  be 
created  by  a  process  of  picking  out  of  individual  differences. 
If,  in  addition  to  this,  Darwin  supposed  that  at  times  varie- 
ties and  species  crowd  each  other  out  nothing  new  is  thereby 
created.*  On  the  other  hand  the  theory  of  the  survival  of 
definite  variations  refers  the  creation  of  new  forms  to  an- 

*"If  the  survival  of  certain  species  determines,  in  a  metaphorical 
sense,  the  kinds  of  future  mutations  that  occur,  the  course  of  evo- 
lution may  appear  to  be  guided  by  selection  or  survival ;  but,  how- 
ever true  it  may  be  that  selection  acts  by  lopping  off  certain 
branches,  and  limits  to  this  extent  the  kinds  of  possible  future  muta- 
tions, the  origin  of  the  new  forms  remains  still  a  different  question 
from  the  question  of  the  survival  of  certain  species.  This  negative 
action  of  selection  is  not  the  process  that  most  Darwinians  have 
had  in  mind  as  the  source  of  the  origin  of  new  species.  It  is  true 
that  Weismann  believes  that  selection  of  individual  differences  deter- 
mines the  origin  of  new  species,  and  that  the  creation  of  these  new 
species  determines  the  future  course  of  variations  in  the  same  direc- 
tion, but  his  argument  that  fluctuating  variations  can  go  on  indefi- 


DARWINISM   ATTACKED.  95 

other  process,  namely,  to  a  sudden  change  in  the  character 
of  the  germ.  The  creating  has  already  taken  place  before 
the  question  of  the  survival  of  the  new  form  comes  up. 
After  the  new  form  has  appeared  the  question  of  its  per- 
sistence will  depend  on  whether  it  can  get  a  foothold.  The 
result  is  now  the  same  as  when  species  crowd  each  other 
out.  This  distinction  appears  to  me  to  be  not  a  matter  of 
secondary  interest,  but  one  of  fundamental  importance,  for 
it  involves  the  whole  question  of  the  'origin  of  species.'  So 
far  as  a  phrase  may  sum  up  the  difference,  it  appears  that 
new  species  are  born;  they  are  not  made  by  Darwinian 
methods,  and  the  theory  of  natural  selection  has  nothing  to 
do  with  the  origin  of  species,  but  with  the  survival  of  already 
formed  species.  Not  selection  of  the  fittest  individuals,  but 
the  survival  of  the  sufficiently  fit  species. 

'There  is  a  fundamental  difference  between  the  idea  that 
fluctuating  variations  become  specific  characters  through 
accumulation  by  selection,  and  the  idea  that  new  species 
arise  as  definite  variations,  which,  with  their  appearance, 
characterise  the  new  form  as  a  new  species.  According" 
to  the  Darwinian  theory,  natural  selection  performs  a  double 
duty,  first,  to  build  up  new  species,  and  second,  to  maintain 
them  in  competition  with  other  species.  According  to  the 
other  view,  species  are  not  formed  by  any  kind  of  selection, 
and  the  question  of  survival  only  concerns  the  maintenance 
of  species  already  formed.  The  primary  problem  is  the 
problem  of  the  'origin  of  species/  The  central  idea  is  not 

nitely  varying  in  the  direction  of  selection  is  refuted  by  what  has 
been  actually  found  to  be  the  case  when  the  process  of  selection  of 
fluctuating  variations  is  carried  out.  Most  of  the  individuals  of  a 
species  may  be  brought  in  this  way  to  show  the  particular  character 
selected  in  its  highest  degree  as  a  fluctuating  variation,  but  it  appears 
not  possible  to  transgress  this  limit ;  and  rigorous  selection  in  every 
generation  is  necessary  to  hold  the  individuals  to  the  highest  point 
reached.  Only  by  the  appearance  of  new  definite  variations  can  a 
given  character  be  permanently  fixed,  or  a  new  species  created  that 
will  show  fluctuating  variations  around  the  new  standard. 


96  DARWINISM   TO-DAY. 

what  species  survive,  but  how  species  originate;  no  matter 
whether  they  are  going  to  become  victorious  or  not. 

"After  a  species  has  appeared  it  will  surely  be  admitted  by 
every  one,  that  forms  that  can  survive  will  survive !  If 
Darwin's  theory  meant  only  this  to  those  who  adopted  it, 
is  it  not  surprising  that  such  a  truism  should  have  been 
hailed  as  a  great  discovery?  Was  not  the  theory  heralded 
because  it  seemed  to  explain  how  new  species  arose  ?  What 
shall  we  say  then  when  we  find  a  situation  like  that  existing 
at  the  present  time,  when  we  are  told  that  after  all  the  only 
difference  between  Darwin's  theory  of  natural  selection  and 
the  theory  of  the  survival  of  definite  variations  is  that  in  the 
one  case  fluctuating  variations  are  selected,  and  in  the  other 
mutations,  and  that  in  both  cases  natural  selection  is  the 
key  to  the  evolutionary  process !  Is  not  the  'origin  of 
species'  still  the  real  point  at  issue? 

"I  yield  to  no  one  in  admiration  for  what  Darwin  has  done 
in  behalf  of  the  biological  sciences,  for  he  succeeded,  where 
the  great  French  zoologists  failed,  in  establishing  the  prin- 
ciple of  evolution.  Furthermore  no  other  hypothesis,  that 
has  as  yet  been  proposed,  accounts  so  well  for  the  wide- 
spread occurrence  of  adaptation  of  organisms  to  the  environ- 
ment as  does  the  principle  of  natural  selection.  But  appre- 
ciation of  Darwin's  claims  in  these  directions  need  not  blind 
us  to  the  insufficiency  of  the  theory  of  natural  selection  to 
account  for  the  origin  of  species;  nor  to  the  fact  that  his 
followers  have  been  especially  concerned  in  propounding 
and  making  application  of  this  side  of  the  theory.  They 
have  shown  little  interest  in  selection  as  the  great  conserv- 
ing factor  of  evolution,  and  the  reason  for  this  is  not  far 
to  seek,  because  of  the  much  greater  importance  that  they 
have  attributed  to  natural  selection  as  a  creative  factor  in 
building  up  individual  differences  into  specific  characters." 


DARWINISM   ATTACKED.  97 


APPENDIX. 

1  De  Vries,  H.,  "Die  Mutationstheorie,"  Vol.  I,  pp.  83    ff.,  1901. 

2  Wolff,  Gustav,  "Der  gegenwartige  Stand  des  Darwinismus,"  p. 
g,  1896. 

3  Weismann,  A.,  "Aufsatze  iiber  Vererbung,"  p.  116,  1892. 

4  Galton,  Francis,  "Natural  Inheritance."     I  quote  from  Galton  as 
follows : 

"As  soon  as  the  character  of  the  problem  of  filial  descent  had 
become  well  understood,  it  was  seen  that  a  general  equation  of 
G-alton's  state-  the  same  form  as  that  by  which  it  was  expressed, 
ment  of  the  law  also  expressed  the  connection  between  kinsmen  in 
of  regression.  every  degree.  The  unexpected  law  of  universal  re- 
gression became  a  theoretical  necessity,  and  on  appealing  to  facts,, 
its  existence  was  found  to  be  conspicuous.  If  the  word  "peculiarity" 
be  used  to  signify  the  difference  between  the  amount  of  any  faculty 
possessed  by  a  man  and  the  average  of  that  possessed  by  the  popu- 
lation at  large,  then  the  law  of  regression  may  be  described  as 
follows :  Every  peculiarity  in  a  man  is*  shared  by  his  kinsmen,  but 
on  the  average  in  a  less  degree.  It  is  reduced  to  a  definite  fraction 
of  its  amount  quite  independently  of  what  its  amount  might  be. 
The  fraction  differs  in  different  orders  of  kin,  becoming  smaller 
as  they  are  more  remote.  When  the  kinship  is  so  distant  that 
its  effects  are  not  worth  taking  into  account,  the  peculiarity  of  .the 
man,  however  remarkable  it  may  have  been,  is  reduced  to  zero  in 
his  kinsmen.  This  apparent  paradox  is  fundamentally  due  to  the 
greater  frequency  of  mediocre  deviations  than  of  extreme  ones, 
occurring  between  limits  separated  by  equal  widths"  (pp.  194-195). 

"The  law  of  regression  in  respect  to  stature  may  be  phrased 
as  follows:  namely,  that  the  deviation  of  the  sons  from  P  are  on 
the  average  equal  to  one-third  of  the  deviation  of  parent  from  P, 
and  in  the  same  direction  or  more  briefly  still;  if  P  -f-  (±D)  be 
the  stature  of  a  parent,  the  stature  of  the  offspring  will  on  the 
average  be  P  +  (±1-3  D)"  (p.  104). 

"Thus,  however  paradoxical  it  may  appear  at  first  sight,  it  is 
theoretically  a  necessary  fact,  and  one  that  is  clearly  confirmed 
by  observation,  that  the  stature  of  the  adult  offspring  must,  on  the 
whole,  be  more  mediocre  than  the  stature  of  their  parents;  that  is 
to  say,  more  near  to  the  M  of  the  general  population"  (p.  95). 

"The  law  of  regression  tells  heavily  against  the  full  hereditary 
transmission  of  any  gift.  Only  a  few  of  many  children  would 
be  likely  to  differ  from  mediocrity  so  widely  as  their  mid-parent, 
and  still  fewer  would  differ  as  widely  as  the  more  exceptional  of 


98  DARWINISM   TO-DAY. 

the  two  parents.  The  more  bountifully  the  parent  is  gifted  by 
Nature,  the  more  rare  will  be  his  good  fortune  if  he  begets  a  son 
who  is  as  richly  endowed  as  himself,  and  still  more  so  if  he  has 
a  son  who  is  endowed  yet  more  largely"  (p.  106). 

6  Morgan,  T.  H.,  "Evolution  and  Adaptation,"  p.  104,  1903. 

6  Johannsen,  W.,  "Uber  Erblichkeit  in  Populationen  und  in  reinen 
Linien,"    1903. 

7  Delage,  Yves,  "L'Heredite,"  2d  ed.,  p.  398,  1903. 

8  Pfeffer,  G.,  "Die  Umwandlung  der  Arten,"  p.  26,  1894. 

9  Wolff,  G.,  "Beitrage  zur  Kritik  der  Darwin'schen  Lehre,"  pp.  50 
ff.    I  quote  as  follows : 

"Fur  jeden,  der  sich  den  Grundgedanken  der  Selektionstheorie 
auch  nur  einigermassen  klar  gemacht  hat,  kann  kein  Zweifel  darii- 
WolfPs  criticism  ber  bestehen,  dass  die  natiirliche  Selektion  immer 
of  panmixia,  nur  ein  einziges  Anpassungsgebilde,  niemals  aber 
zwei  oder  gar  noch  mehr  zu  gleicher  Zeit  ziichten  kann.  Es  konnen 
z.  B.  Auge  und  Ohr  nicht  gleichzeitig  geziichtet  werden,  denn  sonst 
mussten  ja  die  ausgelesenen  Individuen  mit  den  besten  Augen 
zugleich  auch  diejenigen  mit  den  besten  Ohren  sein,  eine  Vorausset- 
zung,  die  wir  um  so  weniger  machen  diirfen,  als  dieselbe  ja  auf 
alle  iibrigen  Organe  ausgedehnt  werden  miisste.  Die  Naturziichtung 
wird  sich  immer  auf  die  Ziichtung  desjenigen  Organes  verlegen, 
dessen  bessere  Ausbildung  fur  das  Tier  den  grosseren  Vorteil 
bietet.1  1st  ein  gutes  Auge  niitzlicher,  als  ein  gutes  Ohr,  so 
sind  die  Individuen  mit  den  besten  Augen  denen  mit  den  besten 
Ohren  gegeniiber  in  Vorteil :  sie  werden  geziichtet.  Wahrend  also 
das  Auge  geziichtet  wird,  steht  das  Ohr  nicht  unter  dem  Einfluss 
der  Selektion,  also  unter  dem  Einfluss  der  Panmixie.  Unter  diesem 
Einflusse  stehen  aber  samtliche  Organe  mit  Ausnahme  des  ein- 
zigen,  welches  gerade  gezuchtet  wird,  sie  fangen  daher  alle  an. 
einen  Riickbildungsprozess  einzugehen.  Sobald  nun  eines  der  nicht 
geziichteten  Organe  bereits  so  weit  riickgebildet  ist,  dass  der  Zu- 
stand  desselben  eine  Gefahr  fur  den  Organismus  in  sich  schliesst, 
alsdann  wird  sich  die  Naturziichtung  diesem  Organe  zuwenden, 
denn  dann  ist  eine  bessere  Ausbildung  dieses  Organes  ein  grosserer 
Vorteil  als  die  des  andern.  Die  Selektion  iiberlasst  also  dieses 
letztere  seinem  Schicksal,  d.  h.  der  riickbildenden  Panmixie,  unter 
deren  Einflusse  die  andern  Organe  immer  noch  stehen. 

1  Jedes  Gebilde,  welches  durch  Naturziichtung  hervorgebracht  istt 
auch  wenn  es  jetzt  von  untergeordneter  Bedeutung  ist,  muss  einm?.l 
Generationen  hindurch.  d.  h.  so  lange  als  die  Selektion  zu  seiner 
Herstellung  brauchte,  das  allerwichtigste  gewesen  sein,  eine  Konse- 
quenz,  die  allein  geniigt,  den  ganzen  Darwinismus  ad  absurdum  zu 
fiihren. 


DARWINISM   ATTACKED.  99 

"Wem  die  Absurditat  dieser  ganz  unvermeidlichen  Konsequenzen 
noch  nicht  einleuchtet,  der  moge  sich  die  Sache  an  einem  Bilde 
versinnlichen.  Wenn  ein  Lehrer  eine  Klasse  von  Schiilern  zu 
unterrichten  hat  und  dabei  so  verfahrt,  dass  er  immer  einen  Schuler 
zu  sich  auf  sein  Zimmer  nimmt  und  dort  unterrichtet,  unterdessen 
aber  die  iibrigen  treiben  lasst,  was  sie  wollen,  so  wird  er  bei  einer 
Inspizierung  durch  den  Schulrat  mit  seiner  Klasse  wenig  Staat 
machen  konnen,  weil  die  Schuler  weit  mehr  Zeit  auf  das  Vergessen, 
als  auf  das  Behalten  und  Lernen  verwendet  haben.  Sie  werden 
daher  nicht  nur  das,  was  sie  bei  diesem  Lehrer  in  den  wenigen 
Einzellektionen,  sondern  auch  das,  was  sie  in  den  friihern  Klassen 
gelernt  hatten,  vergessen  haben.  Genau  so  beim  Organismus.  Alle 
Organe  stehen  eine  weit  langere  Zeit  unter  dem  Einflusse  der  Pan- 
mixie,  als  unter  dem  der  Selektion;  wenn  also  die  Panmixie  einen 
Einfluss  ausiibt,  so  wird  dieser  Einfluss  der  uberwiegende  sein,  und 
wenn  dieser  Einfluss  dem  der  Selektion  entgegengesetzt  ist,  so  wird 
der  Einfluss  der  Selektion  ganzlich  aufgehoben  werden,  d.  h.  der 
riickbildende  Einfluss  wiirde  die  Oberhand  behalten,  das  ganze 
Tier  miisste  sich  mit  Stumpf  und  Stiel — zuriickbilden,  ein  Vorgangr 
bei  welchem  die  Panmixie  zu  vergleichen  ware  einem  Feuer,  das 
ein  Dorf  ergriffen  hat,  die  Selektion  dagegen  einer  Feuerwehr, 
welche  mit  der  Spritze  immer  wieder  an  dasjenige  Haus  fahrt,  aus 
dem  gerade  die  starksten  Flammen  herausschlagen.  Diese  Feuer- 
wehr  wird  gewiss  nicht  viel  von  dem  Dorfe  retten. 

"Der  Darwinismus  muss  also,  wenn  er  der  Absurditat  dieser 
Konsequenzen  entgehen  will,  notwendig  annehmen,  dass  diejenigen 
Organe,  welche  jeweilig  nicht  unter  dem  Einflusse  der  Selek- 
tion stehen,  ruhig  und  unbeschadet  warten  konnen,  bis  die  miitter- 
liche  Sorgfalt  der  Selektion,  welche  sich  immer  nur  einem  ihrer 
Kinder  widmen  kann,  sich  ihrer  wieder  annimmt.  Das  heisst  der 
Darwinismus  muss  annehmen,  dass  die  Panmixie  keinen  Einfluss 
auf  die  Organisation  hat. 

"Da  aber  die  Variierung  eine  Thatsache  ist,  so  muss  er,  anneh- 
men, dass  giinstige  und  ungiinstige  Variierung  die  gleiche  x  Wahr- 
scheinlichkeit  haben,  womit  ein  weiterer  Beweis  geliefert  ist,  dass 
der  Darwinismus  nur  mit  graduellen  Veranderungen  rechnen  kann. 

"Die  Lehre  von  der  Panmixie  und  die  Selektionstheorie  vertragen 
sich  nicht  mit  einander.  Aus  der  Richtigkeit  der  einen  folgt  die 
Falschheit  der  andern.  Und  insofern  die  Selektionstheorie  eigentlich 
die  Voraussetzung  zur  Lehre  von  der  Panmixie  ist,  vernichtet  diese 
letztere  sich  selbst  durch  ihre  blosse  Existenz.  Ihre  Bejahung 

*  Ist  man,  wie  Emery,  der  Ansicht,  dass  ungiinstige  Variierungen 
grossere  Wahrscheinlichkeit  haben  als  giinstige,  so  muss  man 
hieraus  allein  die  Unrichtigkeit  der  Selektionstheorie  folgern. 


ioo  DARWINISM   TO-DAY. 

schliesst  ihre  Verneinting  in  sich,  d.  h.  sie  leidet  an  einem  unlosbaren 
inneren  Widerspruch." 

10  This  necessity  of  constantly  active  selection  must  apply  as  well 
to  specialised  function  as  to  specialised  organ.     But  it  is  not  diffi- 

Exampleof  inef- cult  to  call  attention  to  certain  functions  or  physio- 
fective  panmixia,  logical  capacities  of  various  animals  which  seem  to 
negative  this  declaration  of  the  need  of  constant  selection  to  main- 
tain specialisation.  For  example,  I  have  shown  ("Regeneration  in 
Larval  Legs  of  Silkworms,"  Jour.  Exper,  ZooL,  Vol.  I,  pp.  593-599, 
10  figs.,  1904)  that  the  long  "domesticated"  mulberry  silkworm  larva 
possesses  the  capacity  of  regenerating  any  of  its  legs,  if  the  mutila- 
tion has  not  removed  the  whole  appendage.  Now  the  assumption 
of  most  selectionists  is  that  this  capacity  for  regenerating  injured 
legs  and  other  parts  is  a  specialisation,  adaptive  and  advantageous. 
But  in  connection  with  this  particular  case,  it  should  be  borne  in 
mind  that  the  silkworm  has  been  for  approximately  5,000  years  a 
domesticated  animal,  cared  for  under  such  conditions  as  to  make 
the  natural  loss  of  legs  almost  an  impossible  occurrence.  Perfectly 
protected  against  such  natural  enemies  as  bite  off  legs,  there  has 
certainly  been  nothing  of  that  sharp  necessity,  during  all  the  life  of 
countless  generations  of  silkworms,  which  is  supposed  to  be  the 
basis  for  maintaining  the  advantageous  capacity  for  regeneration. 
There  has  been  a  clear  field  for  panmixia.  But  the  regenerative 
capacity  still  exists  in  effective  degree. 

11  See  a  recent  paper  by  Vejdovsky    ("Uber  einige   Siisswasser- 
Amphipoden,     III.    Die    Augenrediiktion    bei    einem    neuen    Gam- 
Example  of  pro- mar  i  den    aus    Irland    und    iiber    Niphargus    caspary 

gressive  degener-  pratz  aus  den  Brunnen  von  Munchen,"  in  S.  B.  Kgl. 

ation  not  expli-       _,...         ^         ,    .... 

cable  by  natural    Bohm.  Ges.  d.  Wiss.,  1905),  embodying  the  results  of 

selection,  his   studies   on   the   reduction   of   the    size   in   certain 

small  Crustaceans  (Gammaridae),  which  he  found  living  in  the  Irish 
Sea  at  a  depth  of  from  130  to  150  feet.  These  Crustaceans  form 
an  interesting  series  showing  a  gradual  reduction  of  the  eyes.  It  is 
shown  clearly  that  this  reduction  proceeds  very  regularly  from  the 
periphery  toward  the  interior.  First,  there  is  apparent  a  high  degree 
of  variability  of  all  parts,  then  the  optic  parts  of  the  eye  disappear, 
and  finally  the  nervous,  or  retinal,  parts.  This  course  of  reduction 
is  only  explicable,  according  to  the  author,  on  a  basis  of  the 
inherited  degenerative  results  of  a  lack  of  use,  for  in  any  decreas- 
ing use  exactly  this  course  of  individual  degeneration  of  the  eye 
is  what  is  met  with ;  that  is,  the  active  external  optic  elements 
degenerate  first,  and  later  the  nervous,  or  retinal,  elements. 

12  Weismann,  A.,  "On  Germinal  Selection  as  a  Source  of  Definite 
Variation,"  trans.  McCormack,  pp.  38   ff.,  1896. 


DARWINISM   ATTACKED.  101 

18  The  Mayflies,  or  lake-flies,  constitute  an  order  (Ephemerida) 
of  insects  which  spend  from  several  months  to  perhaps  a  couple 
of  years  in  their  immature  life  (as  crawling,  gill-bearing,  wingless 
aquatic  larvae),  and  from  a  few  hours  to  at  most  a  few  days  as 
free-flying  adult  creatures.  Many  other  insects  (indeed  most  in- 
sects) have  a  much  shorter  adult  life  than  immature  life,  and 
most  of  them  have  very  different  structures  in  the  two  life-periods. 
Hundreds  of  insect  kinds  take  no  food  in  the  adult  stage  and  many 
others  that  do  have  food-habits  quite  different  from  the  larval  habits.. 

14  Henslow,  G.  W.,  "Origin  of  Flowering  Structures,"  1895. 

15  Wolff,  G.,  "Beitrage  zur  Kritik  der  Darwin'schen  Lehre,"  pp.  41,. 
ff.,  1898.    I  quote  as  follows : 

"Ware  die  Wahrscheinlichkeit  einer  niitzlichen  Variierung  wirk- 
lich  so  klein,  wie  Emery  behauptet,  ware  sie  wirklich  so  klein,  wie 
Wolff's  discus-  die  Wahrscheinlichkeit,  dass  in  dem  Satz  einer 
sion  of  the  selec-  Druckseite  durch  beliebiges  Ersetzen  eines  beliebigen 
tion  coefficient.  Buchstaben  durch  einen  beliebigen  andern  ein  Druck- 
fehler  verbessert  wird,  dann  konnte  sich  der  Darwinismus  gleich 
von  vornherein  begraben  lassen.  Er  konnte  dann  nicht  mehr  sagen : 
die  Auslese  des  Bessern  muss  notwendig  eine  Steigerung  des 
Niitzlichen  ergeben.  Die  erforderlichen  Voraussetzungen  waren  dann 
noch  viel  verwickelter ;  es  musste  dann  auch  noch  iiber  den  Inten- 
sitatsgrad 1  des  Selektionsprozesses  eine  Voraussetzung  gemacht 
werden :  er  muss  so  hoch  sein,  dass  die  Summe  aller  iiberlebendeii 
±  dx  2  (unter  denen  vor  Eintritt  des  Selektionsprozesses  die  unge- 
heure  Mehrzahl  negativ,  das  Vorhandensein  positiver  dagegen 
ausserst  unwahrscheinlich  war)  eine  positive  Zahl  wird.  Der 
Kampf  urns  Dasein  an  und  fur  sich  niitzt  also  noch  gar  nichts ; 
erst  wenn  er  jenen  ganz  bestimmten  Intensitatsgrad  erreicht,  dann 
erst  wirkt  die  Selektion  verbessernd.  Und  wie  hoch  ist  dieser  von 

1  Dieser    Intensitatsgrad    ist    eine    genau    bestimmte,    wenn    auch 
selten  bestimmbare  Zahl.     Sie  giebt  das  Verhaltnis  der  erzeugten  zu 
den    sich    fortpflanzenden    Nachkommen    an.      Man    konnte    diese 
Verhaltniszahl  den  Selektionskoeffizienten  nennen. 

2  Ich  muss  trotz  der  Einwendungen  Emerys  meine  Schreibweise 
dx  beibehalten.     Sage  ich,   dass  der  Darwinismus  mit   dem  Vari- 
ierungsinkrement  nur  dann  rechnen  diirfe,  wenn  er  von  ihm  keine 
bestimmte  Grosse  voraussetzt,  sondern  ihm  gestattet,  sich  der  Null 
beliebig   zu   nahern,    und    will    ich    dies    durch    ein    mat hemati scries 
Zeichen   ausdriicken,   so  ist   das  einzig  richtige   dx.     Ob   die   wirk- 
lichen    Variierungsinkremente    messbar    sind    oder    nicht,    ist    dabei 
ganz  gleichgiltig.     Ubrigens  ist  Emery  im  Irrtum,  wenn  er  meint, 
alle  seien  messbar.     Die  wenigsten  sind  es.     Die  Differenz  in  der 
Disposition  zur  Tuberkulose  zwischen   zwei   vollig  gesunden   Indi- 
viduen  ist  z.  B.  gewiss  nicht  messbar,  und  doch  kann  gerade  hier 
eine,  wenn  auch  noch  so  kleine  Differenz,  im  Kampf  urns  Dasein 
den  Ausschlag  geben. 


102  DARWINISM   TO-DAY. 

Emery  geforderte  Intensitatsgrad !  Nimmt  man  an,  ein  Tier  habe 
40,000  Millionen  Kinder,  von  welchen  nur  2  Individuen  sich  fort- 
pflanzen,  so  ware  nach  Emerys  Rechnung  dieser  Selektionsprozess 
rnoch  nicht  einmal  intensiv  genug,  um  es  wahrscheinlich  werden  zu 
lassen,  dass  diese  2  im  Durchschnitt  sich  irgendwie  verbessert 
liaben.1  Und  dabei  ist  noch  vorausgesetzt,  dass  die  Selektion  von 
den  40,000  Millionen  wirklich  ganz  genau  die  2  Besten  heraus- 
gefunden  hat.  Dies  wird  natiirlich  nie  der  Fall  sein.  Denn  je 
geringer  die  Prozentzahl  der  giinstigen  Variierungen  ist,  um  so 
weniger  wird  das  Resultat  der  Selektion  von  Variiertmgsvorteilen, 
um  so  mehr  dagegen  von  Situationsvorteilen  abhangen.  Nehmen 
wir  z.  B.  eine  Tierklasse,  bei  welcher  die  Verhaltniszahl  der  erzeug- 
ten  und  der  erhaltungsfahigen  Individuen  der  von  Emery  geforderten 
Zahl  vielleicht  am  nachsten  kommt :  die  Bandwiirmer.  Nehmen 
wir  also  an,  ein  Bandwurm  erzeuge  wahrend  seines  ganzen  Lebens 
40,000  Millionen  Eier.  Unter  den  abgehenden  Eiern  findet  eine 
Selektion  statt :  nur  die,  welche  vom  Zwischenwirt  gefressen  werden 
Iconnen  sich  zur  Finne  entwickeln.  Es  werden  aber  ungeheuer 
wenige  gefressen,  die  meisten  gehen  ungefressen  zu  Grunde.  Wir 
liaben  also  eine  intensive  Selektion.  Wovon  hangt  es  aber  ab,  ob 
das  Ei  gefressen  wird?  Ganz  ausschliesslich  von  aussern  Umstan- 
den.  Die  individuellen  Eigenschaften  der  Eier  kommen  nicht  in 
Betracht.  Wir  haben  also  hier  einen  Selektionsprozess,  bei 
welchem  ein  Einfluss  der  Variierungsvorteile  absolut  ausge- 
schaltet  ist,  bei  welchem  ausschliesslich  Situationsvorteile  in  Be- 
tracht kommen.  Nur  in  Bezug  auf  die  Resistenzfahigkeit  konnten 
Variierungsvorteile  von  Belang  sein,  die  wir  aber  ausschalten 
konnen,  indem  wir  uns  auf  ein  bestimmtes  Anpassungsgebilde 
beschranken  (was  iiberhaupt  bei  jeder  Darwinistischen  Betrachtung 
notig  ist),  z.  B.  die  Entstehung  der  Saugnapfe,  etc.  Dass  unter 
den  relativ  wenigen  gefressenen  Eiern  sich  eines  von  den  2  mit 
einer  in  Bezug  auf  die  Saugnapfe  vorteilhaften  Keimesanlage 
befinde,  ist  ausserst  unwahrscheinlich.  Die  gefressenen  Embryonen 
kommen  nun  'zur  engeren  Wahl.'  Nicht  alle  werden  in  fremden 
Organismus  bleiben.  Viele  werden  einfach  abgehen.  Bei  diesem 
Selektionsprozess,  der  lange  nicht  so  intensiv  ist,  als  der  erste, 

1  Wobei  noch  zu  beachten  ist,  dass  die  Zahl  100  der  Elemente,  in 
welche  Emery  ein  Organ  sich  aufgelost  denkt,  selbstverstandlich 
•eine  willkiirliche  ist,  und  dass  diese  Zahl  der  Wirklichkeit  natiirlich 
um  so  naher  kommen  wird,  je  grosser  sie  angenommen  wird.  Wie 
•enorm  wiirde  sich  dann  erst  die  Zahl  der  Kombinationen  vermehren ! 
TJbrigens  kommt  es  auf  die  Zahlen  gar  nicht  an:  das  Wichtige  ist, 
dass  mit  der  Emeryschen  Annahme  der  Hypothesenkomplex, 
\velchen  die  Selektionstheorie  darstellt,  um  eine  neue  und  zwar  das 
Fundament  betreffende  Hypothese  vermehrt  wurde. 


DARWINISM   ATTACKED.  103 

koimon  auch  (aber  keineswegs  ausschliesslich)  Variierungsvorteile 
mitwirken.  Die  soweit  gelangten  Finnen  kommen  nun  zu  einer 
noch  engern  Wahl.  Nur  diejenigen  entwickeln  sich  waiter,  deren 
Zwischenwirte  gefressen  oder  gegessen  werden.  Diesen  Selektions- 
prozess  konnen  wieder  eine  Unzahl  der  verschiedensten  Faktoren 
beeinflussen.  Mehr  oder  weniger  grosser  Geschmack  an  rohem 
Fleisch,  mehr  oder  weniger  grosse  Achtsamkeit  der  Sanitatsbehor- 
den,  diplomatischer  Notenwechsel  iiber  Grenzverkehr :  das  sind  alles 
Faktoren.  die  in  Betracht  kommen  konnen.  Eine  schneidige  Reichs- 
tagsrede  kann  unter  Umstanden  iiber  Tod  und  Leben  von  Tau- 
senden  von  Bandwurmern  entscheiden.  Eine  Klasse  von  Faktoren 
kommt  aber  ganz  gewiss  nicht  in  Betracht,  das  sind  individuelle 
Vorteile  der  Finnen.  Auch  hier  ist  also  die  Wirkung  der  Vari- 
ierungsvorteile ausgeschaltet.  Unter  den  gefressenen  oder  geges- 
senen  Finnen  findet  wahrscheinlich  wiederum  ein  Selektionsprozess 
statt,  bei  welchem  Variierungsvorteile  (aber  keineswegs  ausschliess- 
lich) mitwirken  konnen.  Von  den  2  Individuen  mit  vorteilhaft 
variierten  Saugnapfen  wird  aber  aller  Wahrscheinlichkeit  nach  kein 
einziges  zur  letzten  Wahl  gekommen  sein.  Also  selbst  bei  denjeni- 
gen  Tieren,  bei  welchen  die  Uberproduktion  die  grosste  ist,  konnte 
nach  der  Emeryschen  Rechnung  die  Selektionstheorie  zur  Erkla- 
rung  der  Anpassungserscheinungen  nicht  mehr  verwendet  werden." 

16  See  Piepers,  M.  C.,  "Mimikry,   Selektion,  Darwinismus,"  1903, 
pp.    376    ff.     Author    shows    how  .an    enormous    mortality    among 
oysters   can   occur   without   any   reference   to   their   fitness   for   lite, 
and    also    gives    other    interesting    cases    of    indiscriminate    non- 
selective  mortality. 

17  Kellogg   and    Bell,    "Studies    of    Variation    in    Insects,"    Proc. 
Wash  Acad.  Sci.,  Vol.  VI,  pp.  203-332,   1904.     I  quote  the  follow- 
ing: 

"There  are  certainly  few  selectionists  left  who  honestly  believe 
that  the  minute  fluctuating  variations  in  pattern,  in  size,  in  curve 
Example  of  non-  of  a   vein,   in   length   of  a   hair,  etc.,  have   that  life- 
selection  of  trivial  and-death  value  which  is  the  sole  sort  of,  value  that 
differences,  an   'advantageous  variation'  must  have  to  be  a  ser- 

viceable handle  for  the  action  of  natural  selection.  As  a  matter 
of  fact,  no  systematist  will  have  escaped  having  had  it  distinctly 
impressed  on  him  that  he  recognises  differences  in  the  pattern  of 
lady-bird  beetles,  in  the  number  of  fin  rays  in  fishes,  in  the  branch- 
ing of  a  vein  in  flies'  wings,  that  no  enemy,  no  agent  of  natural 
selection,  can  recognise,  at  least  to  the  extent  of  pronouncing 
sentence  of  death  (or  not  pronouncing  it)  on  its  basis.  And 
further,  no  biologist  really  satisfies  himself  with  the  worn  state- 
ment, 'We  must  not  presume  to  judge  the  value  of  these  trivial, 


104  DARWINISM   TO-DAY. 

these  microscopic  differences,  for  we  do  not  know  all  the  complex 
interrelation  and  interaction  of  the  organism  and  its  environment/ 
We  do  not,  but  we  do  know  for  many  cases  that  such  differences 
are  actually  not  of  life-and-death  selective  value,  and  reason 
compels  us  to  believe  to  a  moral  certainty  that  in  other  cases  these 
fortuitous  trivialities  have  similar  lack  of  life-and-death  importance. 
The  case  of  the  variation  of  the  convergent  lady-bird  beetle,  Hip- 
podamia  convergens  (p.  275  et  seq.),  is  distinctly  in  point.  In  our 
account  of  this  variation  we  have  called  attention  to  the  suggestive- 
ness,  in  its  light  on  the  rigour  of  the  'struggle  for  existence'  among 
individuals,  of  the  fact  that  among  several  thousand  individuals, 
gathered  together  to  hibernate  after  an  active  life,  having  been 
exposed  to  the  attacks  of  bird  and  insect  enemies,  to  the  rigours 
of  climatic  conditions  and  to  the  necessities  of  obtaining  food 
(other  smaller  insects,  as  aphids,  etc.,  caught  alive),  such  a  range 
of  variation  in  pattern  is  found  as  enables  us  to  describe  (so  that 
they  may  be  actually  readily  distinguished  by  verbal  description), 
eighty-four  'aberrations'  or  pattern-variates ;  lady-birds  with  no 
spots,  with  one,  with  two,  with  three,  with  each  of  all  the  numbers 
up  to  and  including  eighteen  distinct  small  black  spots,  the  different 
numbers  usually  being  represented  by  several  different  combinations 
of  spots.  Systematic  entomologists  describe  Hippodamia  convergens 
as  a  brown-red  beetle  with  six  black  spots  on  each  elytron,  and  this 
description  is  true  for  most  beetles  of  this  species.  But  not  at  all 
for  all;  nor  even  approximately  for  many.  After  a  season  of  ex- 
posure to  the  struggle  for  existence,  to  the  rigours  of  selection, 
individuals  with  one  spot,  with  six  spots,  with  twelve  spots,  with 
eighteen,  find  themselves  alive  and  healthy;  they  come  together 
to  pass  a  quiet  winter  under  the  fallen  oak  leaves  on  a  mountain 
side,  ready  to  mate  miscellaneously  in  the  spring,  and  produce  young 
of  all  manner  of  pattern  (as  far  as  number  and  arrangement  of 
spots  go)  ;  which  young,  whether  twelve-spotted  as  they  ought  to 
be,  or  no-spotted,  or  eighteen-spotted  as  they  may  be,  will  appa- 
rently go  safely  through  life  despite  the  malevolent  search  of  the 
all-powerful  Inquisitor,  Rigour  of  Selection ! 

"Directly  touching  this  point,  too,  are  our  data  of  the  variation 
of  series  of  honey-bees  collected  from  free-flying  individuals  after 
exposure  as  adults  to  the  rigours  of  outdoor  life,  as  compared  with 
the  variation  in  the  series  of  bees,  adult,  but  collected  just  as  issu- 
ing from  the  cells  before  being  exposed  as  adults  in  any  way  to 
the  external  dangers  of  living.  Series  of  both  drones  and  workers 
representing  both  exposed  and  unexposed  individuals  were  studied. 
The  results  of  this  examination  are,  put  in  one  statement,  that  the 
variation  among  the  exposed  individuals  is  no  less  than  that  among; 


DARWINISM   ATTACKED.  105 

the  unexposed  individuals.  This  means  that  these  various,  mostly 
slight,  blastogenic  variations  (although  in  such  important  organs 
as  the  wings)  which  occur  among  bees  at  the  time  of  their  issuance 
as  active,  winged  creatures,  are  not  of  sufficient  advantage  or  dis- 
advantage to  the  individuals  to  lead  to  a  weeding  out  (by  death) 
or  saving  of  such  varying  individuals  by  immediate  selective  action. 
Whatever  the  rigour  and  danger  of  the  outdoor  bee  life,  these 
variations  seem  to  be  insufficient  to  cut  any  figure  in  the  persist- 
ence or  non-persistence  of  any  individual  in  the  face  of  this  rigour." 

18  Conn,  H.  W.,  "The  Method  of  Evolution,"  pp.  72  ff.,  1900. 

19  Wolff,  G.,  "Beitrage  zur  Kritik  der  Darwin'schen  Lehre,"  pp, 
24  et  seq.,  1898. 

20  Plate,   L.,   "Uber  die  Bedeutung  des  Darwin'schen   Selections- 
prinzip,"  pp.  17-18,  1903. 

21  Morgan,  T.  H.,  "Evolution  and  Adaptation,"  1903. 

22  De  Vries,  in  a  recent  paper   ("Altere  und  Neuere  Selektions- 
methode,"  Biol.  Centralbl,  Vol.  XXVI,  pp.  385-395,  1906),  describes 
the  new  methods  of  plant  amelioration  adopted  by  the  Svalfor  Ver- 
suchsstation     (Sweden).     These    methods    have    been    determined 
largely   by   the   acceptance   of    De   Vries's   mutations    theory   as    a 
working  hypothesis. 

23  For  account  of  the  breeding  and  amelioration   (artificial  selec- 
tion)   of   plants    see    Darwin,    "Variation    of    Animals    and    Plants 

References  to  under  Domestication,"  many  editions;  Bailey,  L. 
books  and  papers  H.,  "Plant-breeding,"  4th  ed.,  1906;  Hays,  W.  M., 
on  plant-breed-  "Plant-breeding,"  Bull.  29,  Div.  Veg.  Phys.  and 
inS'  Path.,  U.  S.  Dept.  Agric.,  1901;  Webber,  H.  J., 

and  Bessey,  E.  A.,  "Progress  of  Plant-breeding  in  the  United 
States,"  Yearbook  of  U.  S.  Dept.  AgYlc.,  for  1889,  pp.  465-490; 
Kellogg,  V.  L.,  "The  Scientific  Aspects  of  Luther  Burbank's  Work," 
Pop.  Sci.  Mo.,  pp.  363-374,  Oct.,  1906  (reprinted  in  Appendix  to 
chapter  ix  of  this  book). 

24  Pfeffer,  Georg,  "Die  Umwandlung  der  Arten,"  pp.  19-20,  1894. 

25  De  Vries,  H.,  "Species  and  Varieties,  their  Origin  by  Mutation," 
pp.  798-826,  1905. 

26  Korschinsky,    S.,    "Heterogenesis    und    Evolution,"  Naturwiss. 
Wochenschrift,  Vol.  XIV,  p.  276,  1899. 

27  Coe,  C.  G.,  "Nature  versus  Natural  Selection,"   1894.     A  book 
devoted  wholly  to  denying  any  validity  at  all  to  natural  selection. 

28  Delage,  Yves,  "L'Heredite,"  2d  ed,,  p.  419,  p.  843,  1903. 

29  Morgan,  T.  H.,  "The  Origin  of  Species  through  Selection  Con- 
trasted   with    their    Origin    through    the    Appearance    of    Definite 
Variations,"  Pop.  Sci.  Mo.,  pp.  54-65,  May,  1905. 


CHAPTER  V. 

DARWINISM    ATTACKED     (CONTINUED):    THE 
THEORY  OF  SEXUAL  SELECTION. 

THE  differences  between  male  and  female  individuals  of 
a  single  species  are  often  striking;  recall  the  gorgeous 

colouring,  the  plumes  and  tufts  and  tail-feathers 
sexual  differ-  of  many  male  birds  compared  with  the  sober 

and  quiet  plumage  of  their  mates ;  the  antlers 
of  the  stag,  the  mane  of  the  lion  and  bison,  the  beard  of 
the  goat,  many  monkeys,  and  of  man.  Recall  the  mammae 
of  the  female  quadrupeds,  the  brood  pouches  of  the  female 
kangaroos  and  opossums,  the  small  size,  compared  with  their 
mates,  of  many  female  birds,  the  winglessness  of  many  fe- 
male insects.  Other  less  familiar  kinds  of  animals  show 
sexual  dimorphism  or  dichromatism  in  even  more  striking 
degree,  while  in  many  others  the  differences  are  less  con- 
spicuous but  nevertheless  perfectly  obvious  if  some  attention 
is  given  to  looking  for  them.  These  differences  in  size, 
colour,  general  appearances,  and  various  specific  structural 
details  in  head,  trunk,  wings,  feet,  plumage,  etc.,  are  over 
and  beyond  those  primary  radical  differences  existing  in  all 
species  in  which  the  two  sexes  are  differentiated.  Some  of 
these  differences  may,  however,  have  obvious  relation  to 
the  primary  differences,  in  that  they  may  be  connected  im- 
mediately with  the  act  of  pairing  or  with  the  work  of  rear- 
ing the  young.  The  presence  in  male  insects  of  complexly 
developed  holding  organs,  and  in  female  mammals  of  milk 
glands  exemplifies  differences  of  this  category.  A  great  many 
sexual  differences,  however,  have  no  such  obvious  direct 
relation  to  the  function  of  producing  and  rearing  the  young. 

106 


DARWINISM   ATTACKED.  107 

Such  are  the  metallic  purple  and  bronze  colours  of  the  male 
grackles  compared  with  the  dull  brown  of  the  females  ;  the 
long  tails  and  brilliant  coloration  of  the  male  pheasants, 
the  great,  spreading,  patterned  tail  of  the  peacock,  the 
larger  size  or  the  winglessness  of  many  female  insects,  etc. 
All  these  differences  between  male  and  female  of  the  same 
species  of  animal,  beyond  or  in  addition  to  the  differences 
between  the  actual  primary  reproductive  organs,  are  known 
as  secondary  sexual  differences,  or  the  characters  themselves, 
which  may  be  characteristics  of  physiology  and  habit  as 
well  as  the  more  familiar  ones  of  structure,  are  called  sec- 
ondary sexual  characters.  The  layman  may  not  readily 
appreciate  the  abundance  and  the  great  variety  of  these  char- 
acters, but  it  is.  a  fact  that  almost  all  species  of  animals, 
excepting  those  in  the  lower  invertebrate  branches,  show 
them,  and  if  one  will  try  to  recall  the  aspect  of  the  two 
sexes  in  one  after  another  of  the  species  of  animals  with 
ivhich  one  is  familiar,  mammals,  birds,  insects,  etc.,  one  will 
begin  to  realise  how  widespread  and  significant  are  these 
secondary  sexual  characters. 

Various   biologists   have   made   up   classifications,    from 

various  points  of  view,  of  the  different  kinds  of  these  char- 

acters :  one  classification,  like  that  of  Kramer  * 

Classifications 

of  secondary  sex-  for  the  secondary  sexual  characters  of  insects, 

nal  characters,  n  the  different  parts  of  the  body 


showing  the  differences  between  male  and  female  indi- 
viduals, as  head,  antennae,  thorax,  wings,  legs,  abdomen, 
etc.,  and  on  the  character  of  the  differences  themselves,  as 
whether  differences  in  structure  or  in  colour  and  pattern. 
Another  type  of  classification,  and  one  more  useful  for  our 
present  discussion,  is  that  based  on  the  apparent  significance 
or  actual  use  of  the  differing  characters.  An  excellent 
classification  of  this  type  is  that  of  Plate.2  The  following 
are  the  principal  subdivisions  of  this  classification  with  a 
few  examples  illustrating  each  : 


io8  DARWINISM   TO-DAY. 

CLASSIFICATION    OF    THE    EXTERNAL    SECONDARY    SEXUAL    CHARACTERS. 

Group  A.  Characters  which  are  useful  to  the  possessor,  or  to  its 
young,  or  have  an  indirect  relation  to  reproduction. 

Sub-group  i.  Specialisations  in  organs  which  aid  in  the  finding  of 
individuals  of  the  other  sex.  Examples,  the  extra-develop- 
ment of  the  antennae  in  many  male  moths  and  beetles,  the 
enlarged  and  divided  eyes  of  certain  flies  and  May-flies,  the 
enlarged  tactile  feelers  of  male  Daphnias,  the  larger  or  better 
wings  of  many  male  insects,  the  swimming  membrane,  in  the 
breeding  season,  on  the  hind-legs  of  Molge  paradoxa. 

Sub-group  2.  Specialisations  that  aid  in  mating.  Examples,  the 
clasping  organs  of  many  male  crabs,  the  hectocotylus  of 
octopuses,  the  expanded  tarsi  of  many  male  insects,  and  in 
general,  the  accessory  copulatory  organs  of  innumerable  vari- 
ous animal  species. 

Sub-group  3.  Special  size  and  form  of  the  female  due  to  the  extra- 
development  of  the  ovaries.  Examples,  in  Psychid  moths  and 
parasitic  Crustaceans. 

Sub-group  4.  Differences  connected  with  care  of  the  young.  Ex- 
amples, mammae  of  female  mammals,  brood-pouch  of  mar- 
supials, brood-sacs  of  male  sea-horses,  and  brood-cavities  in 
the  back  of  male  Pip  a  (a  frog). 

Sub-group  5.  Specialisations  for  defence  or  offence.  Examples, 
protective  coloration  of  female  birds  and  insects,  mimicry 
by  female  butterflies,  antlers  of  the  stag,  strong  canines  of 
many  male  mammals  (wild  boars,  etc.),  sting  of  the  female 
honey-bee,  spurs  of  the  cock,  greater  size  and  strength  of 
many  male  mammals  and  birds. 

Sub-group  6.  Differences  in  coloration  which  aid  in  the  recogni- 
tion of  the  sexes  ("recognition  marks"  of  Wallace). 

Sub-group  7.  Differences  connected  with  various  special  habits  of 
life.  Examples,  the  pollen-baskets  of  the  worker  honey-bees, 
the  winglessness  of  male  fig-capri tying  insects  (Blastophaga), 
the  large  differences  between  males  and  females  of  certain 
insects  where  one  sex  lives  parasitically,  the  other  independ- 
ently, as  the  scale  insects,  the  Strepsiptera,  etc.,  the  beak 
differences  in  the  New  Zealand  bird,  Heteralocha  acutiros- 
tris,  whose  male  chisels  out  the  hard  wood  with  a  short, 
broad  beak,  while  the  female  extracts  insect  larvae  from  decay- 
ing wood  by  means  of  a  long,  curved  beak. 

Group  B.  Exciting  organs.  These  are  found  almost  exclusively  in 
the  males  only,  and  serve  to  indicate  the  sexual  excitement 
of  their  possessors,  and  at  the  same  time  to  stimulate  or  excite 


DARWINISM   ATTACKED.  log 

the   females.     The  excitation   of  the  male   is   manifest  to  the 
female  through  her  senses  of  sight,  hearing,  and  smell  (in  each 
case  through  one  or  more  of  these),  and  this  perception  gives 
rise  reflexively  to  an  excitation  on  the  part  of  the  female. 
Sub-group  i.  The  male  characters  may  appeal  to  the  sense  of  sight 
of  the  female:  (a)  by  colours,  as  in  the  breeding  plumage,  or 
coloration,  of  many  birds,  fishes,  amphibians,  and  reptiles,  or, 
as  in  the  constant  brilliancy  of  colour  and  pattern  in  many 
butterflies,  other  insects,  and  spiders;  or  (b)  by  striking  form, 
as    the    beard    and    hairy    tufts    of    many   monkeys    and    the 
extraordinary,  "horns"   and  processes   of  certain   lamellicorn 
beetles;  or  (c)  by  movable  processes  (often  strongly  coloured), 
as  the  wattles  and  movable  feathers  (tail,  etc.)  of  certain  birds, 
swelling  cheek  or  neck  sacs  of  turkeys,  etc.;  or  (d)  by  strik- 
ing movements,  as  the  dancing  on  the  ground  or  tumbling 
and  whirling  in  flight  of  certain  birds,  the  mating-time  bat- 
tles of  mammals,  birds,  and  fishes,  and  the  "love-dances"  of 
spiders. 

Sub-group  2.  The  male  characters  appeal  to  the  sense  of  hearing 
of  the  females,  as  the  song  of  birds,  the  cries  and  calls  of 
many  mammals,  frogs,  and  insects. 

Sub-group  3.  The  male  characters  appeal  to  the  sense  of  smell  of 
the  females,  as  the  odours  given  off  by  goats,  chamois,  musk- 
deer,  beaver,  etc.,  and  from  the  scent-scales  (androconia)  of 
many  male  butterflies. 

Group  C.  Reciprocal  organs;  that  is,  organs  which  exist  in  func- 
tional condition  in  one  sex  but  are  inherited  by  the  other  only 
in  rudimentary  and  often  non-functional  form. 

Examples ;  the  reduced  mammae  of  male  mammals,  the  brood 
pouch  of  the  male  Thylacinus ;  wingless  female  butterflies  often 
have  a  rudimentary  sucking  proboscis,  which  in  some  cases  is  in- 
herited by  the  males  without  any  reduction  of  the  wings ;  in 
cases  of  mimicry  by  female  butterflies,  the  males  often  show 
some  traces  of  the  changed  colour-pattern;  traces  of  spurs  in 
female  pheasants,  reduced  horns  of  female  antelopes  and  goats, 
small  "horns"  on  female  lamellicorn  beetles,  undeveloped  stridu- 
lating  apparatus  in  female  crickets,  katydids,  etc. 
Group  D.  Indifferent  characters,  without  any  apparent  utility. 

Sub-group  i.  Rudimentary  organs,  which  are  wholly  non-func- 
tional in  one  sex,  although  still  functional  in  the  other. 
Examples,  the  reduced  wings  of  many  female  insects,  the 
rudimentary  alimentary  canal  of  male  Rotatoria. 
Sub-group  2.  Negative  characters,  that  is,  those  wholly  failing  in 
one  sex,  although  present  in  the  other.  This  lack  can  be  a 


no  DARWINISM   TO-DAY. 

primary  one,  that  is,  indicate  an  older  phyletic  condition,  as 
the  absence  of  antlers  in  the  female  deer ;  or  be  a  secondary 
one,  that  is,  gradually  acquired  by  progressive  reduction,  as 
the  loss  of  wings  by  many  female  insects. 

Sub-group  3.  Atavistic  characters,  as  the  more  marked  hairiness 
on  the  breast  of  men  as  compared  with  women. 

Sub-group  4.  Correlated  characters,  which  may  be  called  into  ex- 
istence by  other  organs  present ;  with  the  female  mollusc 
Anodonta,  the  shell  is  more  strongly  bowed  in  adaptive 
correlation  with  the  expanded  brood  chamber  between  the 
gills. 

Sub-group  5.  A  large  number  of  secondary  sexual  characters 
which  are  incapable  of  specific  classification,  as  the  minute 
differences  between  the  sexes  in  size  and  habitus;  slight  dif- 
ferences in  wing  form  in  humming-birds,  dragon-flies,  and 
butterflies ;  small  differences  in  character  and  number  of 
tarsal  and  antennal  segments  of  many  insects. 

As  Plate  justly  remarks  the  foregoing  classification  can, 
of   course,   make   no   pretension  to   completeness.     But   it 

indicates  sufficiently  clearly  certain  important 
Apparent  sig-  J  * 

nificanceofthe  differences  among  the  secondary  sexual  cnar- 
ciaracters,  acters ;  differences  especially  important  in  con- 
nection with  any  attempt  to  get  at  an  explanation  of  the 
why  and  how  of  these  characters.  Such  a  classification 
shows  that  many  of  these  characters  have  uses  which  are 
of  a  kind  directly  helpful  in  the  struggle  for  existence,  as  the 
strong  antlers  of  the  stags,  useful  in  defence  against  attacking 
enemies ;  the  brood  sacs  of  the  kangaroos  and  opossum,  use- 
ful in  caring  for  their  helpless  young;  the  milk-glands  and 
teats  of  all  female  mammals,  the  pollen-baskets  and  wax- 
glands  of  the  honey-bee  which  make  the  workers  more 
'  effective  food-gatherers  and  food-storers,  and  the  protective 
colours  and  patterns  of  many  insects  and  birds.  But  others, 
many  others,  indeed,  of  these  secondary  sexual  characters, 
are  either  of  a  kind  apparently  useless  in  the  struggle  for 
life,  or  even  of  a  kind  actually  harmful.  Of  apparent  useless- 
ness  are  the  reduced  wings  of  some  male  insects,  and  the 
host  of  slight  differences  in  coloration,  pattern,  size,  or 


DARWINISM   ATTACKED.  m 

shape,  of  different  body-parts  or  of  the  whole  body,  the 
beards  and  hair-tufts  of  many  male  mammals  and  the  combs 
and  wattles  of  male  gallinaceous  birds.  Of  apparent  harm- 
fulness  are  those  ultra-developed  pro-thoracic  and  head 
processes,  "horns,"  of  stag  and  other  lamellicorn  beetles,  the 
conspicuous  staring  colours  of  many  male  birds,  the  long 
dangling  plumes,  the  weighty  crests,  and  heavy  dragging 
tails  of  others,  all  these  parts  also  usually  being  dangerously 
conspicuously  coloured.  The  lively  loud  song  of  many 
male  birds,  and  the  dancing  and  leaping  of  numerous  male 
spiders  and  some  male  birds  must  also  involve  some  danger 
to  the  performers  by  attracting  the  attention  of  their  enemies. 
In  fact  most  of  those  secondary  sexual  characters  that  are 
classified  under  the  general  head  of  "exciting  organs"  are 
apparently  of  a  sort  that  should  be  actually  disadvantageous 
in  the  struggle  for  existence.  They  are  of  a  character  tend- 
ing to  make  their  possessors  conspicuous  and  thus  readily 
perceived  by  their  carnivorous  enemies.  How  is  to  be 
explained  the  existence  of  so  many  and  such  highly  de- 
veloped structural  and  physiological  characters  of  this  kind, 
a  condition  that  seems  to  stand  in  direct  opposition  to  the 
theory  of  natural  selection  ?  Darwin's  answer  to  this  ques- 
tion is  contained  in  his  theory  of  sexual  selection. 

This  theory,  in  few  words,  is  that  there  is  practically  a 

competition  or  struggle  for  mating,  and  that  those  males  are 

_      .  ,   ,        successful  in  this  struggle  which  are  the  stron- 

Darwin's  the- 
ory of  sexual        gest  and  best  equipped  for  battle  among  them- 

selection,  selves,  or  which  are  most  acceptable,  by  reason 

of  ornament  or  other  attractiveness,  to  the  females.  In  the 
former  case  mating  with  a  certain  female  depends  upon 
overcoming  in  fight  the  other  suitors,  the  female  being  the 
passive  reward  of  the  victor;  in  the  second  case  the  female 
is  presumed  to  exercise  a  choice,  this  choice  depending  upon 
the  attractiveness  of  the  male  (due  to  colour,  pattern,  plumes, 
processes,  odour,  song,  etc.).  The  actual  fighting  among 


112  DARWINISM   TO-DAY. 

males  and  the  winning  of  the  females  by  the  victor,  are  ob- 
served facts  in  the  life  of  numerous  animal  species.  But  a 
special  sexual  selection  theory  is  hardly  necessary  to  explain 
the  development  of  the  fighting  equipment,  antlers,  spurs, 
claws,  etc.  This  fighting  array  of  the  male  is  simply  a  special 
phase  of  the  already  recognised  intra-specific  struggle ;  it  is 
not  a  fight  for  room  or  food,  but  for  the  chance  to  mate. 
But  this  chance  often  depends  on  the  issue  of  a  life-and- 
death  struggle.  Natural  selection  would  thus  account  for 
the  development  of  the  weapons  for  this  struggle. 

For  the  development,  however,  of  such  secondary  sexual 
characters  as  ornament,  whether  of  special  plumage,  colour, 
pattern,  or  processes,  and  song,  and  special  odours,  and 
"love-dancing,"  the  natural  selection  theory  can  in  no  way 
account;  the  theory  of  sexual  selection  was  the  logical  and 
necessary  auxiliary  theory,  and  when  first  proposed  by 
Darwin  3  met  with  quick  and  wide  acceptance.  Wallace  in 
particular  took  up  the  theory  and  applied  it  to  explain  many 
cases  of  remarkable  plumage  and  pattern  development 
among  birds.  Later  as  he  analysed  more  carefully  his  cases, 
and  those  proposed  by  others,  he  became  doubtful,  and 
finally  wholly  sceptical 4  of  the  theory. 

The  theory  as  proposed  by  Darwin  was  based  on  the  fol- 
lowing general  assumptions,  for  the  proof  of  each  of  which  a 
few  to  many  facts  were  adduced.  First,  many 
bases  of  the  secondary  sexual  characters  are  not  explicable 
by  natural  selection ;  they  are  not  useful  in  the 
struggle  for  life.  Second,  the  males  seek  the  females  for 
the  sake  of  pairing.  Third,  the  males  are  more  abundant 
than  the  females.  Fourth,  in  many  cases  there  is  a  struggle 
among  the  males  for  the  possession  of  the  females.  Fifth, 
in  many  other  cases  the  females  choose,  in  general,  those 
males  specially  distinguished  by  more  brilliant  colours,  more 
conspicuous  ornaments,  or  other  attractive  characters. 
Sixth,  many  males  sing,  or  dance,  or  otherwise  draw  to 


DARWINISM   ATTACKED.  113 

themselves  the  attention  of  the  females,  Seventh,  the  sec- 
ondary sexual  characters  are  especially  variable.  Darwin 
believed  that  he  had  observed  certain  other  conditions  to  ex- 
ist which  helped  make  the  sexual  selection  theory  probable, 
but  the  conditions  noted  are  sufficient  if  they  truly  exist. 

Exposed  to  careful  scrutiny  and  criticism— an  admira- 
ble and  convincing  example  of  such  scientific  and  impar- 
tial   criticism    is    Kramer's    analysis    of    the 

Scrutiny  and 

criticism  of  the  secondary  sexual  characters  of  European  m- 
theory,  sects — ^Q  theory  of  sexual  selection  has  been 

relieved  of  all  necessity  of  explaining  any  but  two  categories 
of  secondary  sexual  characters,  namely  the  special  weapons 
borne  by  males,  and  the  special  ornaments  and  excitatory 
organs  of  the  males  and  females.  For  examination  has 
disclosed  the  fact  that  males  are  not  alone  5  in  the  possession 
of  special  characters  of  attraction  or  excitation.  Regarding 
these  two  categories  Plate,6  in  his  able  recent  defence  of 
Darwinism,  says,  "the  first  part  of  this  theory,  the  origin  of 
the  special  defensive  and  offensive  weapons  of  males  through 
sexual  selection  is  nearly  universally  accepted.  The  second 
part  of  the  theory,  the  origin  of  exciting  organs  has  given 
rise  to  much  controversy.  Undoubtedly  the  presumption 
that  the  females  compare  the  males  and  then  choose  only 
those  which  have  the  most  attractive  colours,  the  finest  song, 
or  the  most  agreeable  odour,  presents  great  difficulties,  but 
it  is  doubtful  if  it  is  possible  to  replace  this  explanation 
by  a  better."  Some  of  these  difficulties  may  be  briefly 
enumerated. 

The  theory  can  be  applied  only  to  species  in  which  the 

males  are  markedly  more  numerous  than  the  females,  or  in 

which  the   males   are   polygamous.     In   other 

Males  must  be  f  .„"  .         t       ..  t 

more  numerous  cases  there  will  be  a  female  for  each  male 
than  females,  or  whether  he  be  ornamented  or  not;  and  the 

he  polygamous, 

unornamented  males  can  leave  as  many  progeny 
as  the  ornamented  ones,  which  would  prevent  any  cumula- 


114  DARWINISM   TO-DAY. 

tion  of  ornamental  variations  by  selection.  As  a  matter  of 
fact  in  a  majority  of  animal  species,  at  least  among  the 
vertebrates,  males  and  females  exist  in  approximately  equal 
numbers. 

Observation  shows  that  in  most  species  the  female  is 
wholly  passive  in  the  matter  of  pairing,  accepting  the  first 
Female  is  usn-  ma^e  that  offers.  Note  the  cock  and  hens  in 
ally  passive.  the  barnyard. 

Ornamental  colours  are  as  often  a  characteristic  of  males 

of  kinds  of  animals  in  which  there  is  no  real  pairing,  as 

among:   those   which    pair.      How    explain   by 

Ornaments  oc-  * 

cur  on  males  that  sexual  selection  the  remarkable  colours  in  the 
do  not  pair,  breeding  season  of  many  fishes,  in  which  the 
female  never,  perhaps,  even  sees  the  male  which  fertilises 
her  dropped  eggs? 

Choice  on  a  basis  of  ornament  and  attractiveness  implies 
a  high  degree  of  aesthetic  development  on  the  part  of  the 

females  of  animals  for  whose  development  in 
asthSlvelop-  this  line  we  have  no  (other)  proof.  Indeed  this 
ment  in  lower  choice  demands  aesthetic  recognition  among 
animals. 

animals   to   which   we   distinctly   deny   such   a 

development,  as  the  butterflies  and  other  insects  in  which 
secondary  sexual  characters  of  colour,  etc.,  are  abundant 
and  conspicuous.  Similarly  with  practically  all  invertebrate 
animals.  Further,  in  those  groups  of  higher  animals  where 
aesthetic  choice  may  be  presumed  possible  we  have  repeated 
evidence  that  preferences  vary  with  individuals.  Certainly 
they  do  with  man,  the  animal  species  in  which  such  prefer- 
ences certainly  and  most  conspicuously  exist.  In  some 
human  races  hair  on  the  face  is  thought  beautiful ;  in  others, 
ugly.  Besides  even  if  we  may  attribute  fairly  a  certain 
amount  of  aesthetic  feeling  to  such  animals  as  mammals  and 
birds,  is  this  feeling  to  be  so  keen  as  to  lead  the  female 
to  make  choice  among  only  slightly  differing  patterns  of 
songs  ?  Yet  this  assumption  is  necessary  if  the  development 


DARWINISM    ATTACKED.  i«5 

of  ornament  and  other  attracting  and  exciting  organs  is  to 
be  explained  by  the  selection  and  gradual  cumulation  through 
generations  of  slight  fortuitously  appearing  fluctuating 
variations  in  the  males. 

There  are  actually  very  few  recorded  cases  where  the 
observer  believes  that  he  has  noted  an  actual  choice  by  a 
Few  observed  ^ema^e-  Darwin  records  eight  cases  among 
cases  of  choice  birds.  Since  Darwin  not  more  than  half  a 
byfemae,  dozen  other  cases,  all  doubtful,  have  been 
recorded.  Also  a  few  instances,  all  more  illustrative  of 
sexual  excitation  of  females  resulting  from  the  perception 
of  odour  or  actions,  than  any  degree  of  choice  by  females, 
have  been  listed. 

In  numerous  cases  the  so-called  attractive  characters  of 
the  males,  described  usually  from  preserved  (museum) 
specimens,  have  been  found,  in  actual  life,  to 
'  be  °f  sucn  a  character  that  they  cannot  be  noted 


acters  not  visible  by    the    female.      For    example,    the    brilliant 

in  nature,  . 

colours  and  the  curious  horns  of  the  males 
of  the  dung  beetles  are,  in  life,  always  so  obscured  by  dirt 
and  filth  that  there  can  be  no  question  of  display  to  the 
female  eyes  about  them.  The  dancing  swarms  of  many 
kinds  of  insects  are  found  to  be  composed  of  males  alone 
with  no  females  near  enough  to  see;  it  is  no  case  of  an 
excitatory  flitting  and  whirling  of  many  males  before  the 
eyes  of  the  impressionable  females.  Of  many  male  katy- 
dids singing  in  the  shrubbery  will  not  for  any  female  that 
particular  song  be  the  loudest  and  the  most  convincing  that 
proceeds  from  the  nearest  male,  not  the  most  expert  or  the 
strongest  stridulator?  Similarly  with  the  flitting  male  fire- 
flies; will  not  the  strongest  gleam  be,  for  any  female,  that 
from  the  male  which  happens  to  fly  nearest  her,  and  not 
from  the  distant  male  with  ever  so  much  better,  stronger 
light? 

Stolzmann  finds  it  difficult  to  understand,  when  nearly 


n6  DARWINISM   TO-DAY. 

related  species  differ  widely  in  their  ornamental  plumage, 

that  this  should  be  attributed  to  a  difference  in 

Problem  of       preference  among  the  females  of  the  related 

the  Andean  .   &  . 

humming-birds,  species.  The  humming-bird,  Schist es  perso- 
natus,  lives  in  Ecuador  on  the  west  side  of  the 
Andes,  in  a  restricted  range  of  four  degrees  of  latitude.  It 
is  distinguished  from  the  nearly  related  Schist  es  geoffroyi 
.especially  in  the  possession  by  its  male  of  a  brilliant  spot  over 
each  eye.  Schist  es  geoffroyi  lives  on  the  east  side  of  the 
Andes  from  Colombia  to  Central  Peru,  with  a  range  cover- 
ing over  twenty  degrees  of  latitude,  which  range  is  divided 
into  two  completely  separated  regions  by  the  Marafion 
valley.  Now  if  isolation  alone  is  sufficient  to  produce  a 
change  in  the  taste  of  the  females,  one  would  expect  to  find 
two  sorts  of  males  (as  far  as  ornamental  pattern  goes)  in- 
side this  one  species.  But  there  is  but  one  kind  of  male 
through  the  whole  range.  Why  is  the  taste  of  the  female 
constant  through  twenty  degrees  of  latitude,  while  it  is 
changed  on  the  other  side  of  the  Andes  in  a  limited  range 
of  four  degrees  of  latitude?  Another  case  presented  by 
Stolzmann  is  even  more  striking.  The  Chilian  hummer, 
Eustephanns  galeritus,  which  is  green  in  both  sexes,  has 
migrated  from  the  continent  to  the  Juan  Fernandez  Islands. 
On  Masatierra  Island  it  has  changed  to  Bust,  fernandensis, 
in  Masafuera  Island  to  Eust.  leyboldi.  These  two  species 
agree  in  the  females  with  the  original  continental  form 
(that  is,  are  green)  while  the  males  have  become  red,  but  in 
different  pattern  in  the  two  species.  Eust.  galeritus  (the 
Continental  form)  also  occurs  on  Masatierra  Island,  in  the 
same  form  as  on  the  continent,  that  is,  with  green  male. 
Now  one  must  presume  from  this  state  of  affairs  that_this 
species  (galeritus)  has  been  able  to  reach  Masatierra  twice, 
once  long  ago — the  descendants  of  the  invasion  having 
changed  to  Eust.  fernandensis — and  once  more  recently — 
the  descendants  of  these  later  migrants  showing  as  yet  no 


DARWINISM   ATTACKED.  n? 

sign  of  a  transformation  of  the  male  colour.  Shall  one  in  this 
case  and  others  like  it,  asks  Stolzmann,  assume  a  change  of 
beauty-ideal  on  the  part  of  the  females  ?  Much'  simpler  and 
much  more  reasonable,  according  to  Stolzmann,  is  it  to  see  in 
the  change  of  colour  of  the  males  of  the  earlier  migrants  the 
results  of  the  direct  influence  of  the  new  environment;  the 
islands  are  distinctly  milder  and  warmer  than  the  continent. 
Even  if  the  females  do  choose  among  the  males  on  a  basis 
of  attractiveness,  how  are  the  characters  of  the  more  at- 
tractive males  to  become  especially  fostered 
attractive  char-  an<^  accumulated  by  selection?  Do  such  males 

acterstobe  produce  more  offspring  or  more  vigorous  ones 
fostered?  ,  .  , 

than  the  other  males,  which,  though  rejected 

by  the  first  females,  find  their  mates  among  the  females  not 
already  mated  ?  Are  we  to  attribute  to  the  more  ornamental 
males  a  particular  vigour?  If  so,  may  not  that  very  vigour 
be  the  cause  of  the  extra-production  of  colour  or  plumage 
or  wattles,  etc.? 

Darwin  admits,  in  order  to  explain  the  beginnings  of 
colour  and  ornament  development,  a  certain  degree  of  differ- 
ence between  the  male  and  female  in  regard  to 

Darwin's  Big- 

nificant  admis-  their  reaction  to  environmental  influences.  If 
slon'  so,  may  not  these  admitted  differences  be  really 

sufficient  to  account  for  even  a  pretty  high  degree  of  differ- 
ence in  development  of  secondary  sexual  characters  ? 

The  special  display  of  colours,  tufts,  plumes,  spreading 
tails,  and  other  secondary  sexual  characters  by  the  males  at 
mating  time  is  an  observed  fact;  the  "dances" 
of  cranes  and  storks,  the  serenades  of  the  song- 
birds, the  evolutions  of  the  male  spiders  are  all 
familiar  phenomena  in  the  mating  season  of  these  animals. 
And  they  probably  do  exercise  an  exciting  effect  on  the 
females,  and  are  probably  actually  displayed  for  this  pur- 
pose. But  does  this  in  any  way  prove,  or  even  give  basis 
for  a  reasonable  presumption  for  belief  in  a  discriminating 


DARWINISM   TO-DAY. 

and  definitive  choice  among  the  males  on  the  part  of  the 
female?  And  it  is  this  actual  choosing  which  is  the  neces- 
sary basis  for  the  theory  of  sexual  selection. 

How  explain  the  well-known  cases  of  a  similar  extra- 
development   of   plumage   in   the   nuptial    season   by   both 
Bow  explain      males  and  females,  as   in  certain   herons  and 
ornaments  in       other  birds  ?     And  what  of  those  other  cases  in 

females  or  ....  ,. 

common  to  both  which  it  is  the  female  that  is  the  bnghter-col- 
sexes  ?  oured  individual  of  the  pair  ?  To  explain  the  lat- 

ter case  Darwin  assumes  that  in  these  cases  the  males  have 
done  the  selecting,  but  even  this  rather  too  easy  reversal  of 
the  situation  postulated  as  a  fundamental  generalisation 
of  the  theory  does  not  explain  the  first  of  the  questions  in 
this  paragraph.  Do  both  sexes  among  the  herons  do 
selecting  ? 

Morgan  7  lists  twenty  objections  to  the  sexual  selection 

theory,  several  of  which  are  identical  with  those  already 

mentioned   in   the    foregoing   paragraphs,    but 

Morgan's  list     arnOng  which  are  several  to  which  we  have  not 

of  objections! 

referred.  One  of  these  is  that  "some  of  the 
objections  that  apply  to  the  theory  of  natural  selection 
apply  also  with  equal  force  to  the  theory  of  sexual  selection 
in  so  far  as  the  results  in  both  cases  are  supposed  to  be  the 
outcome  of  the  selection  of  individual,  or  fluctuating,  varia- 
tions. If  these  variations  appear  in  only  a  few  individuals, 
their  perpetuation  is  not  possible,  since  they  will  soon  dis- 
appear through  crossing.  It  would  be,  of  course,  preposter- 
ous to  suppose  that  at  any  one  time  only  those  few  indi- 
viduals pair  and  leave  descendants  that  have  secondary 
sexual  characters  developed  to  the  highest  point,  but  if 
something  of  this  sort  does  not  occur,  the  extreme  of 
fluctuating  variations  cannot  be  maintained.  Even  if  half 
of  the  individuals  are  selected  in  each  generation,  the  ac- 
cumulation of  a  variation  in  a  given  direction  could  not  go 
very  far.  The  assumption,  however,  that  only  half  of  all 


DARWINISM   ATTACKED.  119 

the  individuals  that  reach  maturity  breed,  and  that  all  of 
these  are  chosen  on  account  of  the  special  development  of 
their  secondary  sexual  characters,  seems  preposterous. 
Furthermore,  if  it  is  assumed  that  the  high  development  of 
the  new  character  appears  in  a  large  number  of  individuals, 
then  it  is  not  improbable  that  its  continued  appearance  might 
be  accounted  for  without  bringing  in,  at  all,  the  hypothesis 
of  sexual  selection." 

Again,  Morgan  well  points  out  that  "the  development,  or 
the  presence,  of  the  aesthetic  feeling  in  the  selecting  sex  is  not 
accounted  for  on  the  theory.  There  is  just  as  much  need  to 
explain  why  the  females  are  gifted  with  an  appreciation  of  the 
beautiful  as  why  the  beautiful  colours  develop  in  the  males. 
Shall  we  assume  that  still  another  process  of  selection  is  go- 
ing on,  as  a  result  of  which  those  females  are  selected  by  the 
males  that  appreciate  their  unusual  beauty,  or  that  those 
females  whose  taste  has  soared  a  little  higher  than  that  of  the 
average  (a  variation  of  this  sort  having  appeared)  select 
males  to  correspond,  and  thus  the  two  continue  heaping 
up  the  ornaments  on  one  side  and  the  appreciation  of  these 
ornaments  on  the  other?  No  doubt  an  interesting  fiction 
could  be  built  up  along  these  lines,  but  would  any  one  be- 
lieve it,  and  if  he  did,  could  he  prove  it? 

"Darwin  assumes  that  the  appreciation  on  the  part  of 
the  female  is  always  present,  and  he  thus  simplifies,  in 
appearance,  the  problem,  but  he  leaves  half  of  it  un- 
explained. 

"There  is  another  side  to  the  question,"  also  says  Morgan, 
"the  importance  of  which  is  so  great,  that  it  is  surprising 
that  Darwin  has  not  taken  any  notice  of  it.  If,  in  order  to 
bring  about,  or  even  maintain,  the  results  of  sexual  selection, 
such  a  tremendous  elimination  of  individuals  must  take 
place,  it  is  surprising  that  natural  selection  would  not 
counteract  this  by  destroying  those  species  in  which  a 
process,  so  useless  for  the  welfare  of  the  species,  is  going 


120  DARWINISM   TO-DAY. 

on.  It  is  curious  that  this  has  not  been  realised  by  those 
who  believe  in  both  of  these  two  hypotheses. 

"What  has  just  been  said  applies  also  with  almost  equal 
force  to  the  development  of  such  structures  as  the  horns 
of  the  deer,  bison,  antelopes,  and  the  brilliant  colours  of 
many  insects  and  birds.  If  in  nature,  competition  between 
species  takes  place  on  the  scale  that  the  Darwinian  theory 
of  natural  selection  postulates,  such  forms,  if  they  are  much 
exposed,  would  be  needlessly  reduced  in  numbers  in  the 
process  of  acquiring  these  structures.  So  many  individuals 
would  have  been  at  such  a  disadvantage  in  breeding,  that 
if  competition  is  as  severe  as  the  theory  of  natural  selection 
postulates,  these  species  could  hardly  be  expected  to  compete 
successfully  with  other  species  in  which  sexual  selection  was 
not  taking  place." 

Finally  to  make  an  end  of  miscellaneous  objections  and 

come  to  that  one  which  promises  to  be,  if  it  is  not  already, 

the  most  serious  obstacle  in  the  way  of  the 

evidence Ts^p-     sexual  selection  theory,  it  is  a  fact  that  all  the 

posed  to  sexual     evidence  (though  it  be  little  as  yet)  based  on 

selection  theory.  '          . 

actual  experiment  is  strongly  opposed  to  the 

validity  of  the  assumption  that  the  females  make  a  choice 
among  males  based  on  the  presence  in  the  males  of  ornament 
or  attractive  colours,  pattern,  or  special  structures.  I  may 
mention  especially  the  striking  experiments  of  Mayer 8 
(which,  published  in  a  small  entomological  journal  of 
limited  circulation,  have  not  received  the  attention  that  they 
deserve)  on  the  large  Bombycine  moth,  Callosamia  pro- 
methea.  This  well-known  American  moth  expands  about 
three  and  one-half  inches  and  shows  unusually  pronounced 
secondary  sexual  differences  as  to  colour  and  pattern.  The 
females  are  reddish-brown  in  ground  colour,  while  the  males 
are  blackish  and  in  the  two  sexes  the  pattern  is  distinctly 
different.  If  there  is  any  moth  species  in  which  the  colours 
and  general  pattern  of  the  male  ought  to  be  readily  obvious 


DARWINISM   ATTACKED.  121 

to  the  female,  and  in  which  sexual  selection  might  be  pre- 
sumed to  have  been  the  influence  in  producing  a  pronounced 

male    type    of    preferred    pattern,    it    is    this 
Mayer's  ex- 
periments on       species.     Mayers   simple  and -convincing   ex- 

Promethea.  periments  were  as  follows  :  Mayer  took  four 
hundred  and  forty-nine  pupae  (in  cocoons)  of  the  moth 
Callosamia  promethea,  which  had  been  collected  in  Massa- 
chusetts and  New  Jersey,  south  to  Loggerhead  Key  in  the 
Dry  Tortugas  Islands  off  Florida.  This  island  is  separated 
by  many  miles  of  ocean  from  other  land,  and  is  hundreds 
of  miles  south  of  the  range  of  the  species.  Evidently  no 
interference  with  Mayer's  experiments  could  come  from 
outside  individuals  of  this  species.  The  moths  issued  during 
May  and  June  in  the  proportion  of  about  two  males  for- 
each  female.  The  males  of  this  species  seek  out  the  female 
for  pairing  and  can  do  this  for  a  considerable  distance.  As 
many  as  several  dozen  males  will  find  a  single  female  and 
hover,  fluttering,  about  her.  Mayer's  first  experiments  were 
directed  to  the  end  of  determining  if  the  males  found  the 
females  by  sight  or  by  smell.  By  enclosing  females  in 
numerous  jars  variously  arranged  and  covered  or  uncovered, 
it  was  readily  determinable  that  males  never  pay  any 
attention  to  females  enclosed  in  transparent  jars  so  closed 
as  to  prevent  the  escape  of  any  odours  from  the  female, 
while  to  females  enclosed  in  boxes  or  wrapped  in  cotton  so 
as  to  be  invisible  but  yet  capable  of  giving  odour  off  into 
the  air  males  came  promptly  and  hovered  about.  To  locate 
the  organs  of  scent  in  the  female  Mayer  cut  off  abdomens 
from  various  females  and  then  placed  abdomens  and  ab- 
domenless  females  at  some  little  distance  apart.  Males 
came  to  the  abdomens  and  not  to  the  thorax  plus  wings, 
legs,  and  head  parts.  Females  were  proved  to  increase  in 
attractive  power  with  age,  and  virgins  are  a  little,  but  only 
a  little,  more  attractive  than  already  fertilised  females.  It 
was  readily  proved,  by  experiments  with  males  whose  an- 


122  DARWINISM   TO-DAY. 

tennae  were  covered  with  shellac,  photographic  paste,  glue, 
paraffin,  etc.,  that  the  sense  of  smell  is  seated  in  the  antennae. 
Males  with  antennae  covered  with  photographic  paste  did 
not  find  females,  while  the  same  males  with  this  paste  dis- 
solved off  did. 

Mayer  now  tried  to  test  the  selective  action  of  the  female. 
The  male  promethea  has  blackish  wings  while  the  females 
are  reddish-brown.  In  accordance  with  the  theory  of 
sexual  selection,  the  peculiar  coloration  of  the  male  should 
be  due  to  the  selection  of  dark-coloured  males,  so  that 
tinder  this  influence  the  males  would  become,  in  successive 
generations,  darker  and  darker  until  the  present  coloration 
has  been  attained.  Mayer's  own  account  of  his  experi- 
ments and  conclusions  to  test  the  preferences  and  selective 
action  of  the  females  is  as  follows : 

"In  order  to  test  this  hypothesis  I  cut  off  the  wings  of  a 
number  of  females,  leaving  only  short  stumps,  from  which 
all  the  scales  were  carefully  brushed.  Male  wings  were 
then  neatly  glued  to  the  stumps,  and  thus  the  female  pre- 
sented the  appearance  of  a  male.  Under  these  circum- 
stances the  males  mated  with  the  female  quite  as  readily  as 
they  would  have  done  under  normal  conditions. 

"I  then  tried  the  experiment  of  gluing  female  wings  upon 
the  male.  Here  again  the  mating  seemed  to  occur  with 
normal  frequency,  and  I  was  unable  to  detect  that  the 
females  displayed  any  unusual  aversion  toward  their 
•effeminate-looking  consorts. 

"It  is  also  interesting  to  note  that  normal  males  pay  no 
attention  to  males  with  female  wings.  - 

"In  another  series  of  experiments  the  wings  were  cut 
entirely  off  of  males  and  females  and  the  scales  brushed 
off  their  bodies ;  and  yet  these  shabby  males  were  readily 
accepted  by  normal  females,  nor  could  I  see  that  normal 
males  displayed  any  aversion  to  mating  with  wingless 
females. 


DARWINISM   ATTACKED.  123 

"We  are  therefore  forced  to  conclude  that  the  melanic 
coloration  of  the  male  has  not  been  brought  about  through 
the  agency  of  sexual  selection  on  the  part  of  the  female." 

More  recently  Mayer  (and  Soule)  *  repeated  these  experi- 
ments on  a  more  extensive  scale  and  with  some  variations 
in  character.  Fifteen  hundred  cocoons  of 

Mayer  ana 

Sonie's  experi-  Promethea  were  collected  in  the  winter  of  1901- 
02  and  hung  in  trees  so  that  the  issuing  moths 
might  fly  about  unconfined.  "About  six  hundred  males 
emerged  from  the  cocoons  and  the  wings  of  about  one-half 
of  them  were  painted  with  scarlet  or  green  ink,  while  the 
others  were  allowed  to  remain  normal  in  colour.  It  was 
evident  that  the  males  whose  wings  were  scarlet  and  green 
succeeded  fully  as  well  in  their  attempts  to  mate  as  did  the 
normal  males." 

Experiments  were  also  tried  with  the  moth  Porthetria 
dispar,  in  which  the  male  is  brown  and  the  female  white. 
The  experiments  showed  that  males  with  wings  painted 
scarlet  or  green  were  accepted  as  readily  as  normal  males, 
but  that  males  with  the  wings  cut  off  were  more  apt  to  meet 
with  resistance  from  the  females  than  perfect  males  were. 
From  these  experiments  Mayer  and  Soule  conclude  that  the 
mating  instinct  in  the  males  of  C.  promethea  and  P.  dispar 
is  a  phenomenon  of  chemotaxis.  Sexual  selection  on  the 
ground  of  colour  alone  does  not  affect  it,  and  there  is  no 
associative  memory  connected  with  it. 

To  these  experiments  may  be  added  the  observations  of 

Douglass,10    who    found   that    females    of   the    wall-lizard, 

Lacerta.  muralis,  showed  no  preference  what- 

onEUzPardsmeiltS     Cver  among  the  variable  patterns  exhibited  by 
males  in  breeding-coat.     Diirigen 1X   observed 
that   male   lizards   without   tails   are   accepted   readily   by 
females. 

Finally,  also,  of  the  nature  of  objections  to  the  sexual 
.selection  theory  are  the  replacing  or  substutionary  explana- 


124  DARWINISM   TO-DAY. 

tions  of  secondary  sexual  characters  which  various  biol- 
ogists have  offered.  These  explanations  will  be  presented 
Alternative  ex-  in  some  detail  in  chapter  xi,  which  is  devoted 
oidarysexulr0" to  an  exposition  of  the  various  alternative 
characters,  theories  proposed  to  replace  or  partially  to  re- 
place the  Darwinian  theories.  It  must  be  sufficient  to  say  here 
that  the  theories  proposed  to  account  for  secondary  sexual 
characters  mostly  rest  on  one  or  both  of  two  principal  basic 
assumptions ;  first,  that  the  secondary  sexual  characters  are 
produced  as  the  result  of  the  immediate  stimulus  (naturally 
different)  of  the  sexually  differing  primary  reproductive 
organs,  this  stimulus  being  usually  considered  to  result 
from  an  internal  secretion  of  the  genital  organs  acting  on 
certain  tissues  of  the  organism ;  and,  second,  that  the  males 
in  most  species  possess  an  excess  of  energy  which  manifests 
itself  in  extra-growths,  extra-development  of  pigment, 
plumage,  etc.,  and  that  displays  by  the  males  of  special  move- 
ments, sound-making,  etc.,  are  direct  effects  or  manifesta- 
tions of  sexual  excitation.  To  these  explanations  should  be 
added  the  rather  far-fetched  one  of  Emery,  who  believes  that 
many  cases  of  secondary  sexual  differences  are  explained  by 
the  sudden  appearance  (mutation)  of  another  form  of  male 
or  female,  the  persistence  for  a  while  of  the  two  forms  side 
by  side,  as  now  exists  in  numerous  dimorphic  species  (espe- 
cially among  insects),  and  then  the  gradual  dying  out  (kill- 
ing out  by  natural  selection)  of  one  of  the  two  old  original 
forms  (the  one  like  the  other  sex),  thus  leaving  the  other, 
or  aberrant  form.  The  ideas  of  Cunningham,12  who  does 
not  believe  that  any  selection  of  fortuitous  variation  can 
account  for  secondary  sexual  characters,  may  also  be  re- 
ferred to.  In  a  book  of  over  three  hundred  pages  this 
author  lists  and  describes — according  to  principal  animal 
groups — a  host  of  secondary  sexual  characters,  and  pro- 
poses a  theory  to  account  for  them.  ''The  direct  effects," 
writes  Cunningham,  "of  regularly  recurrent  stimulations  are 


DARWINISM   ATTACKED.  125 

sooner  or  later  developed  by  heredity,  but  only  in  associa- 
tion with  the  physiological  conditions  under  which  they  were 
originally  produced.  This  is  the  explanation  of  the  limita- 
tions of  particular  modifications  not  merely  to  particular 
species  or  kinships,  but  to  particular  periods  in  the  life  of 
the  individual,  to  a  particular  sex  and  even  to  a  particular 
season  of  the  year  in  that  sex."  The  author  believes  that  an 
examination  of  secondary  sexual  characters  shows  that  they 
develop  at  places  and  in  parts  which  are  at  the  time  of 
sexual  excitement  unusually  directly  stimulated  by  exertion 
or  contact  or  use.  These  secondary  sexual  characters  are 
"in  many  cases  not  merely  limited  to  the  period  of  mature 
life  but  actually  to  that  part  of  the  year  in  which  the  repro- 
ductive organs  are  active,  that  is  to  the  breeding  season." 

In  closing  this  chapter  given  up  to  objections  to  the  Dar- 
winian theories  of  natural  and  sexual  selection,  attention 

may  be  called  to  Wolff's  13  objection  to  natural 
Importance  of    selection  based  upon  the  dependence  of  the  na- 

tural  selection  theory  on  the  sexual   selection 


support  of  the      theory  for  explanation  of  the  existence  of  orna- 

natural  selection 

theory.  mental  characters,  and  of  all  these  secondary 

sexual  characters,  which  are  useless  or  even 
apparently  disadvantageous  in  the  life-and-death  inter- 
specific struggle  for  space  and  food.  As  Wolff  looks  on  the 
sexual  selection  theory  as  wholly  discredited,  he  finds  this 
necessary  dependence  on  it  by  believers  in  natural  selection 
for  the  explanation  of  those  characters  just  mentioned 
strong  evidence  for  the  weakness  of  the  natural  selection 
theory. 

APPENDIX. 

1  Kramer,  Paul,  "Theorie  u.  Erfahrung  ;  Beitrage  zur  Beurtheilung 
des  Darwinismus,"  1877,  Halle.  An  interesting  paper  criticising 
the  selection  theories  from  two  points  of  view  ;  first,  on  the  basis  of 
a  mathematical  treatment  of  the  Darwinian  hypothesis  (especially 
that  of  sexual  selection),  the  author  taking  Darwin's  premises  and 
by  a  mathematical  handling  of  them  showing  that  they  do  not  lead 


126  DARWINISM   TO-DAY. 

to  the  Darwinian  conclusions ;  and,  second,  on  a  basis  of  the  care- 
ful scrutiny  of  the  facts  of  secondary  sexual  differences,  the  author 
finding  sexual  selection  wholly  unable  to  account  for  the  great 
majority  of  secondary  sexual  characters  among  animals. 

2  Plate,  L.,  "Uber  die  Bedeutung  des  Darwin'schen  Selections- 
prinzips,"  pp.  107-111,  2d.  ed.,  1903,  Leipzig. 

8  Darwin  outlined  the  theory  of  sexual  selection  in  the  "Origin 
of  Species"  (1859),  but  first  treated  it  at  length  in  the  "Descent  of 
Man"  (Parts  II  and  III),  1871. 

4  Wallace,  A.  R.,  "Tropical  Nature,"  chap,  v,  1878;  and  "Darwin- 
ism," chap,  x,  1891,  London. 

6  Doane  (Ent.  News,  Vol.  XVIII,  pp.  136-138,  1907)  has  described 
the  striking  behaviour  during  mating  of  certain  Dolichopodid  flies 
(Scellus  virago,  n.  sp.)  observed  by  him  on  the  salt  marsh  flats 
of  San  Francisco  Bay,  near  Stanford  University.  In  these  matings 
it  is  the  female  which  is  the  active  sex  in  pursuing  and  exciting 
the  other. 

6  See  note  2. 

I  Morgan,    T.    H.,    "Evolution    and    Adaptation,"    chap,    vi,    1903, 
New  York.     This  chapter  is  an  exhaustive  attack  on  the  theory  of 
sexual  selection. 

8  Mayer,  A.  G.,  "On  the  Mating  Instinct  in  Moths,"  Psyche,  Vol. 
IX,  pp.  15-20,  1900. 

9  Mayer,    A.    G.,   and    Soule,    C.    G.,    "Some   Reactions  of   Cater- 
pillars and  Moths,"  Jour.  Exper.  ZooL,  Vol.  Ill,  pp.  427-431,  1906. 

10  Douglass,    N.    G.,    "On   the    Darwinian    Hypothesis   of   Sexual 
Selection,"  Nat.  Science,  Vol.  VII,  pp.,  398-406,  1895. 

II  Diirigen,  "Deutschlands  Amphibien  u.  Reptilien,"  p.  89,  1897. 

12  Cunningham,  J.  T.,  "Sexual  Dimorphism  in  the  Animal  King- 
dom," 1900. 

13  Wolff,  Gustav,  "Beitrage  zur  Kritik  der  Darwin'schen  Lehre/* 
p.  21    ff.,  1898,  Leipzig.    A  bitter  but  keen  and  trenchant  critical  ex- 
position of  certain  weaknesses  in  the  selection  theories.     He  criti- 
cises the  theory  of  sexual  selection  in  the  following  words : 

"An  diese  Falle  reiht  sich  vielleicht  am  besten  die  Betrachtung 
der  Folgen,  welche  fruhzeitige  Sterilitat  auf  die  Ausbildung  von 
Wolff's  exposi-  sekundaren  Geschlechtscharakteren  ausubt.  Wir  kon- 
tionofweak-  •  nen  ja  diese  Erscheinungen  auch  in  gewissem  Sinne 
nesses  in  sexual  zu  den  Ruckbildungen  rechnen ;  sie  haben  aber  insbe- 
selection,  sondere  auch  das  mit  den  vorigen  Fallen  gemeinsam, 

dass  wir  hier  ebenfalls  einen  im  individuellen  Leben  des  Organismus 
sich  abspielenden  Vorgang  beobachten  konnen,  der  nach  der  Selek- 
tionstheorie  nicht  eintreten  durfte. 

"Nach  der  Selektionstheorie  entstehen  ja  sekundare  Geschlechts- 


DARWINISM   ATTACKED.  127 

merkmale  dadurch,  dass  eben  Individuen  des  einen  Geschlechts,  bei 
welchen  durch  zufallige  Variierung  eine  Andeutung  solch  eines 
Merkmals  da  war,  mehr  Chancen  batten,  sich  fortzupflanzen  und 
diese  Eigentiimlichkeit  auf  die  Nachkommen  ihres  Geschlechts  zu 
vererben,  von  denen  dann  durch  den  gleichen  Prozess  immer 
diejenigen  zur  Fortpflanzung  ausgewahlt  wurden,  welche  die  betref- 
fende  Eigentiimlichkeit  am  starksten  besassen.  Es  soil  also  zwischen 
jenen  Gebilden  und  dem  Geschafte  der  Zeugung  an  und  fur  sich. 
nicht  der  geringste  Zusammenhang  existieren.  Dann  ist  aber 
schwer  erklarlich,  warum  jene  sekundaren  Geschlechtsmerkmale. 
sich  haufig  nur  zur  Zeit  der  Geschlechtsthatigkeit  bilden  und  nachher 
wieder  verschwinden,  wie  z.  B.  der  Hochzeitskamm  der  Tritonen. 
Aber  geben  wir  einmal  zu,  das  sei  bloss  ein  zufalliges  Zusammen- 
treffen,  indem  eben  diejenigen  zur  Fortpflanzung  gelangten,  welche 
gerade  zufallig  um  die  Zeit  der  Brunst  eine  bald  wieder  zufallig; 
verschwindende  Verstiirkung  des  Kammes  besassen.  Es  ist  zwar 
unmoglich,  sich  dies,  insbesondere  das  Verschwinden  des  Kammes, 
vorzustellen,  weil  ja,  wenn  auch  das  spatere  Verschwinden  des 
Kammes  dem  Tiere  irgend  einen  Vorteil  gebracht  haben  sollte, 
dieser  bei  der  Selektion  in  keiner  Weise  sich  geltend  machen  konnte, 
oder  doch  nur  in  Bezug  auf  das  Individuum  aber  nicht  auf  dessert 
Nachkommen,  aber  nehmen  wir  einmal  an,  das  sei  alles  in  Ordnung : 
wie  erklart  sich  dann,  dass,  z.  B.  beim  kastrierten  Hirsch  keia 
Geweih  sich  entwickelt,  dass  der  kastrierte  Mensch  hohe  Stimme 
behalt,  keinen  Bart  bekommt  u.  s.  w.,  u.  s.  w.? 

"Auch  andere  Riickbildungen,  welche  nach  Aufhoren  der  Ge- 
schlechtsthatigkeit normal  sich  einstellen  (z.  B.  Aufhoren  der  Flim- 
merbewegung  im  Uterus  des  Weibes  nach  Aufhoren  der  Menstrua- 
tion, Verlust  der  Fliigel  nach  der  Begattung  bei  Insekten,*  etc.),  bieten 
der  Selektion  die  grossten  Schwierigkeiten,  denn  wenn  hier  die 
Riickbildung  einen  Vorteil  bote,  welcher  die  Auswahl  der  Indi- 
viduen, bei  welchen  diese  Riickbildung  auftrat  herbeifiihrte,  so 
konnte  dieser  Selektionsprozess  doch  erst  nach  der  Fortpflanzungs- 
zeit  eintreten,  auf  die  nachfolgenden  Geschlechter  daher  von  keinem: 
Einflusse  mehr  sein. 

"Der  unbestreitbare  Zusammenhang,  welcher  zwischen  der  Ge- 
schlechtsthatigkeit und  den  sekundaren  Geschlechtsmerkmalen 
besteht,  ist  nun  aber  nicht  etwa  durch  das  Wort  'Korrelatior/ 
erklart.  Es  ist  natiirlich  richtig,  dass  eine  Anderung  irgend  eine 
andere  im  Gefolge  haben  kann,  dass  es  also  korrelative  Abande- 
rungen  giebt,  aber  ist  denn  damit  vielleicht  erklart,  dass  eine 
bestimmte  zweckmassige  Abanderung  nun  auch  eine  andere  fur 

*In  diesem  letzteren  Fall  ist  vielleicht  doch  ein  Vorteil  fur  die 
Art  durch  Vermittlung  der  Brutpflege  denkbar. 


128  DARWINISM   TO-DAY. 

den  jeweilig  vorliegenden  ganz  speziellen  Fall  niitzliche  Abande- 
rung  bedingt?  Korrelative  Abanderungen  beziehen  sich  ja  in  den 
meisten  Fallen,  wo  wir  von  solchen  sprechen,  auf  ganz  bestimmte 
Verhaltnisse  der  Aussenwelt.  Sich  zur  Erklarung  solcher  Erschein- 
ungen  mit  der  Konstatierung  eines  Gesetzes  der  Korrelation 
zufrieden  geben,  heisst  einfach  eine  praestabilierte  Harmonic 
zwischen  der  Entwicklung  der  Organismen  und  den  Verhaltnissen 
der  Aussenwelt  annehmen.  Das  Ratselhafte  ist  ja  zunachst  nicht 
der  Umstand,  dass  es  iiberhaupt  Korrelationserscheinungen  giebt 
(wenngleich  wir  naturlich  auch  hierfiir  ebensowenig,  wie 
fiir  irgend  eine  andere  Lebenserscheinung  eine  Erklarung  haben), 
sondern  der  Umstand,  dass  eine  Eigentumlichkeit  eine  andere 
•korrelativ  im  Gefolge  hat,  die  eben  gerade  fur  besondere 
aussere  Zwecke  vorteilhaft  ist.  Hier  kann  die  Selektionstheorie 
nichts  ausrichten,  denn  der  Selektionsprozess  hat  doch  keinen  Ein- 
fluss  auf  die  Variierungsgesetze,  zu  welchen  die  Korrelationsge- 
setze  gehoren;  diese  miissen  vielmehr  vorausgesetzt  werden. 

"Es  giebt  ubrigens  Thatsachen,  die  mir  darauf  hinzudeuten  schei- 
nen,  dass  die  korrelativen  Beziehungen  noch  viel  verwickelter  sind, 
und  dass  korrelative  Beziehungen  gar  nicht  immer  auf  die  Ent- 
stehung  korrelativer  Abanderungen  zuriickzufiihren  sind,  sondern 
dass,  was  ja  noch  viel  ratselhafter  ist,  eine  Korrelation  erst  sekundiir 
erworben  werden  kann,  wie  folgendes  Beispiel  zeigen  diirfte. 

"Von  den  drei  verschiedenen  Individuen  des  Bienenstaates  hat 
nur  die  Arbeitsbiene  an  der  Innenflache  des  Tarsus  regelmassige 
Borstenreihen,  sogenannte  Biirstchen.  Da  die  Arbeitsteilung  immer 
eine  hohere  Differenzierung  ist,  so  kann  es  keinem  Zweifel  unter- 
liegen,  dass  urspriinglich  bei  alien  Formen  die  Beine  gleich  waren. 
Kaum  zu  entscheiden  diirfte  wohl  die  Frage  sein,  ob  urspriinglich 
sich  die  Burstchen  sowohl  bei  mannlichen  als  auch  bei  weiblichen 
Individuen  differenzierten,  sodass  das  Fehlen  derselben  bei  den 
Drohnen  als  Ruckbildung  betrachtet  werden  musste,  oder  ob  die 
Burstchen  gleich  von  vornherein  als  sekundares  Geschlechtsmerkmal 
der  Weibchen  auftraten.  Im  erstern  Fall  ware  also  die  Bildung 
primar  in  keinerlei  Korrelation  zum  Geschlechtsapparate  gestanden, 
diese  miisste  vielmehr  erst  spater  erworben  worden  sein.  Im 
zweiten  Fall  waren  die  Burstchen  als  zum  Geschlechtsapparate 
korrelative  Bildungen  entstanden,  aber  in  beiden  Fallen  musste 
eine  Anderung  des  Korrelationsverhaltnisses  eingetreten  sein,  die 
Korrelation  musste  namlich  eine  reziproke  werden :  die  Entstehnng 
von  Burstchen  ist  zwar  an  das  weibliche  Geschlecht  gekniipft, 
jedoch  in  der  Weise,  dass  die  Burstchen  nur  auftreten,  wenn  die 
Geschlechtsorgane  nicht  zur  Ausbildung  kommen." 


CHAPTER  VI. 
DARWINISM  DEFENDED. 

IN  taking  up  the  defence  of  Darwinism  it  should  be  noted 
in  the  first  place  that  the  anti-Darwinians  are  without  the 
walls  ;  that  theirs  is  the  burden  of  attack  ;  that 
against  them  is  the  presumption  of  right.    The 


defenders  of        Darwinians  are  in  the  castle,  theirs  simply  the 

Darwinism, 

necessity  of  withstanding  or  repelling  really 
significant  and  truly  threatening  attack;  theirs  the  strength 
of  possession  and  the  presumption  of  truth.  Much  anti- 
Darwinism  is  futile  and  easily  answered  ;  much  was  an- 
swered by  Darwin  *  himself  before  ever  the  anti-Darwinians 
formulated  it  ;  much  other  anti-Darwinism  is  directed  against 
a  position  which  Darwinism,  true  Darwinism,  has  long  seen 
the  inadvisability,  indeed  the  impossibility,  of  holding. 
With  certain  concessions  made,  what  use  of  further  struggle 
over  them  ?  Thus  by  answering  briefly  the  insignificant  and 
undamaging  part  of  anti-Darwinian  attack,  or  by  referring 
to  Darwin's  own  answers  of  this,  and  by  indicating  clearly 
and  definitely  the  concessions  that  Darwinism  is  ready  to 
make,  has  made,  indeed  —  these  humiliating  concessions,  if 
humiliation  is  in  them,  only  being  made  necessary  because 

*Darwin's  anticipation  of  the  criticisms  of  his  theories,  and  his 
own  open-minded  and  detailed  answers  to  these  criticisms,  should, 
of  course,  be  held  clearly  in  mind  by  any  student  of  fur-und- 
gcgen  Darwinismus.  but  many  of  these  answers  concern  objections 
which  present-day  Darwinism  has  largely  conceded  as  valid,  and 
most  of  the  others  touch  matters  on  which  modern  biological  re- 
search has  thrown  much  new  light.  So  that  it  is  perhaps  fairer 
to  the  Darwinian  theories  to  set  out  the  attitude  of  present-day 
Darwinians.  For  a  detailed  critical  consideration  of  Darwin's  own 
answers,  see  Morgan,  "Evolution  and  Adaptation"  (1903). 

129 


130  DARWINISM   TO-DAY. 

of  the  ill  judgment  and  rash  enthusiasm  of  certain  too 
ardent  and  too  conspicuous  friends  of  Darwinism,  the  so- 
called  neo-Darwinians — with  this  salutary  restriction  of 
diffuseness  in  account,  "Darwinism  Defended"  may  be  con- 
fined to  fewer  pages  than  have  been  devoted  to  "Darwinism 
Attacked"  without  suggesting  by  this  brevity  any  necessary 
weakness  in  the  Darwinian  position. 

Let  us  give  our  first  attention  to  the  Darwinian  conces- 
sions— those  concessions  which  the  biological  world  has 
Eeaction  practically  agreed  have  been  made  necessary  by 
against  ultra-  the  steady  criticism  of  the  exaggeration  and 
magnification,  almost  wholly  post-Darwinian  in 
appearance,  of  the  Darwinian  factors  in  evolution.  It  is 
strange,  but  wholly  true,  that  the  modern  reaction  and  revolt 
against  Darwinism  is  chiefly  due  to  the  activity  and  attitude 
taken  by  certain  of  its  over-ardent  friends.  Weismann,  by 
denying  validity  to  any  other  evolutionary  factor  than  the 
natural  selection  of  purely  congenital  variations,  and  by  the 
development  to  an  illogical  and  untenable  extreme  of  his 
theory  of  the  independence  and  continuity  of  the  germ- 
plasm,  precipitated  the  revolt  and  furnished  the  enemy  with 
the  very  weapons  needed  to  overcome  neo-Darwinism. 
The  evolution  champion  Haeckel,  although  not  at  all  a 
Weismannian  Darwinian,  has  also  by  his  daring  and  reck- 
less speculative  development  of  certain  phases  of  evolution- 
ary thought,  especially  in  its  relation  to  sociology  and 
religious  philosophy,  and  by  his  obstinate  adherence  to,  and 
reiteration  of,  certain  long  discredited  more  strictly  biological 

dogmas  of  evolutionary  science,  contributed  to 
Haeokeli 

produce  an  irritation  and  antagonistic  activity 
among  biologists,  especially  in  Germany,  which  has  helped 
make  many  friends  for  the  anti-Darwinian  party.  "Der 
Haeckelismus  in  der  Zoologie," '"  as  Semper  originally 
phrased  it,  is  the  object  of  a  curiously  bitter  and  often- 
expressed  contempt  in  German  biological  circles.  I  fancy 


DARWINISM   DEFENDED.  131 

that  this  feeling  really  depends  not  so  much  on  Haeckel's 
attitude  and  speculative  writing  in  zoology  as  in  his  unpar- 
donable intrusion  into  politics  and  religion;  the  Social- 
Democrats  and  the  Free-Thinkers  have  found  a  helpful  and 
willing  scientific  champion  in  Haeckel.  And  this  is  sin 
superlative  in  rigorous  minds!  As  a  matter  of  fact,  how- 
ever, biologists  generally  are  agreed  that  Haeckel's  daring 
speculations  and  reckless  progress  in  advance  of  positions 
grounded  on  observed  fact  have  been,  in  a  way,  always  repre- 
hensible and  dangerous  to  the  fair  fame  of  biological  science. 
But,  to  my  mind,  biologists  may  also  fairly  agree  that  this 
very  activity  and  speculative  daring  of  Haeckel  have  in- 
spired much  genuine  biological  investigation  (for  the  sake 
of  denying  or  confirming  his  speculations)  and  have  led  to 
a  salutary  reactionary  critical  attitude  toward  other  biologi- 
cal speculations  and  hypotheses.  It  is  a  rare  ism  in  any 
science  or  philosophy  that  yields  nothing  good. 

Weismannism  is  wholly  different  from  Haeckelism.  It 
has  only  in  common  with  it  that  it  is,  in  part,  also  daringly 
speculative.  But  the  speculations  primarily  interest  neither 
Free-Thinkers  nor  Social-Democrats.  They  have  to  do 
with  the  ultimate  structure  and  behaviour  of  protoplasm, 
especially  germinal  protoplasm,  and  with  the  intimate  proc- 
esses of  heredity  and  variation. 

Weismann  first  attempted  to  free  Darwin's  general  theory 
of  modification  and  species-forming  from  all  taint  of  La- 
marckism;  an  attempt  which  resulted  in  his 
theories15""1'8  apparently  successful  overthrowal  of  the  com- 
monly accepted  theory  of  the  inheritance  of 
acquired  characters,  a  theory  or  assumption  which  is  a 
fundamental  and  indispensable  part  of  the  general  Lamarck- 
ian  theory.  (Lamarckism  and  the  inheritance  of  acquired 
characters  are  explained  and  briefly  discussed  in  chapter,  x  of 
this  book.)  On  the  strength  of  this  success  Weismann  pro- 
posed the  doctrine  of  the  Allmacht  of  natural  selection ;  that 


132  DARWINISM   TO-DAY. 

is,  that  natural  selection  alone  is  capable  of  explaining  all  the 
phenomena  and  facts  of  species-forming  and  descent.  At 
the  same  time  he  developed  and  announced  the  theory  of  the 
continuity  of  the  germ-plasm,2  which,  in  a  word,  is  the 
theory  of  an  absolute  separation  of  the  germ-plasm  from 
the  soma-plasm  and  consequently  the  thorough  independ- 
ence of  this  germ-plasm  from  all  influence  and  control  of 
the  soma-plasm,  i.  e.,  all  that  part  of  the  body  other  than 
the  germ  cells.  This  carried  with  it  the  assumption  that 
all  the  phenomena  of  heredity  and  variation  depended  solely 
on  the  germ-plasm  and  that  the  germ-plasm  of  any  individual 
is  derived,  unmodified  by  any  somatic  influences,  directly 
from  the  germ-plasm  of  its  ancestors.  This  assumption  in 
turn  led  to  the  logical  but  startling  conclusion  that  all  the 
capacity  or  possibility  of  variation  for  all  time  was  present 
in  that  primitive  ancestral  germ-plasm  from  which  the  germ- 
plasm  of  all  many-celled  animals  has  been  derived.  But  such 
a  nearly  infinite  capacity  for  furnishing  variations  demanded 
the  postulation  of  an  equally  nearly  infinite  capacity  for  ac- 
tual physical  or  structural  complexity  on  the  part  of  the  germ- 
plasm  itself,  for  biologists  insist  on  a  physical  mechanism  for 
all  the  physiological  phenomena  they  find  in  life.  So  Weis- 
mann  assumed  an  interesting  but  invisible  and  apparently 
non-testable  composition  of  germ-plasm  out  of  life-units, 
called  biophors,  grouped  into  particles  of  a  second  order  called 
determinants.  The  biophors  are  taken  to  be  much  larger 
and  more  complex  units  than  chemical  atoms,  or  even  than 
molecules.  They  are  groups  of  several  to  many  molecules, 
each  biophor,  however,  still  ultra-microscopic,  and  represent- 
ing a  single  characteristic  of  cell-life.  Each  biophor  is  as- 
sumed to  possess  the  essential  attributes  of  living  substance, 
viz.,  the  capacity  to  assimilate  food,  to  grow,  and  to  repro- 
duce itself.  The  groups  of  biophors  called  determinants 
are  larger,  of  course,  but  yet  invisible  to  oUr  best  micro- 
scopes, and  each  represents  all  the  characteristics  which  a 


DARWINISM   DEFENDED.  133 

cell  of  any  particular  single  kind  has.  Thus  one  kind  of 
determinant  represents  all  the  attributes  of  the  red  blood 
corpuscles,  another  of  the  nerve-ganglion  cells,  another  of  a 
certain  type  of  epithelial  cells,  and  so  on.  Each  determinant 
has  also  the  power  of  assimilating  food,  growing  and  re- 
producing itself  by  division.  Now  the  possibility  of  repre- 
senting in  the  germ-plasm  the  nearly  infinite  capacity  to 
vary  characteristic  of  this  plasm  has  for  its  physical  or 
mechanical  basis  the  minute  size  of  the  biophors  and  deter- 
minants coupled  with  the  inconceivably  many  combinations 
of  different  kinds  of  biophors  possible  in  the  make-up  of  the 
determinants  which  are,  as  already  said,  the  actual  structural 
representatives  of,  or  better,  controllers  or  producers  of, 
the  various  kinds  of  body  tissue  and  organs. 

These  three  general  assumptions  of  Weismann,8  namely, 
( i )  the  composition  of  germ-plasm  out  of  ultimate  life-units 
called  biophors  (grouped  into  determinants)  which  deter- 
mine all  the  physical  characteristics  of  the  individuals  into 
which  the  germ-plasm  develops;  (2)  the  isolation  (from  the 
soma)  and  the  continuity  (from  generation  to  generation, 
from  beginning  to  end)  of  the  germ-plasm;  and  (3)  the 
Allmacht  of  natural  selection,  which  involves  the  discarding 
of  all  other  factors  of  modification  and  species-forming  than 
the  natural  selection  of  the  slight  fluctuating  congenital 
variations  produced  (in  an  unknown  manner)  by  infinitesi- 
mal changes  in  the  determinants  of  the  germ-plasm — these 
three  fundamental  and  important  Weismannian  assumptions, 
accepted  more  or  less  nearly  completely  by  Wallace  and  a 
.  number  of  other  English  biologists,  and  by  a 
ismandNeo-  few  naturalists  of  Europe  and  America,  con- 
amarckism,  stitute  the  essential  position  of  what  is  called 
neo-Darwinism.  This  neo-Darwinism  immediately  found 
many  capable  antagonists,  and  as  most  of  the  antago- 
nists were  believers  in  some  parts  of  the  general  theory 
of  adaptation  and  species-forming  first  proposed  by 


134  DARWINISM   TO-DAY. 

Lamarck,  their  position  came  to  be  known  as  neo- 
Lamarckism.  Herbert  Spencer  in  England,  Packard, 
Osborn,  and  others  in  America,  and  Eimer  in  Ger- 
many were  prominent  exponents  of  the  anti-Weisman- 
nian  views.  The  debate  was  spirited,  and  engaged  many 
biological  writers,  and  interested  the  general  reading 
public  in  the  larger  problems  of  biology  more  than  it 
has  been  interested  at  any  other  time  since  the  great  struggle 
immediately  following  the  publication  of  Darwin's  "Origin 
of  Species."  The  best  known  part  of  the  general  debate 
was  that  carried  on  directly  by  Weismann  and  Spencer  in 
the  Contemporary  Review  (1893  and  1894). 

The  general  result  of  the  struggle  between  neo-Darwin- 

ism  and  neo-Lamarckism  can  be  fairly  stated  to  be,  that 

Weismann's  assault  on  the  theory  of  the  in- 

Concessipns  of   heritance  °f  acquired  characters  was  in  general 
xi  co-Darwinians. 

successful ;  while,  on  the  other  hand,  the  assault 
of  the  anti-Weismannians  on  the  assumptions  of  the  isola- 
tion and  continuity  of  the  germ-plasm  and  of  the  Allmacht 
of  natural  selection  forced  from  Weismann  and  his  follow- 
ers, one  by  one  and  slowly,  such  radical  concessions  as  to 
make  the  latter  doctrine  utterly  untenable,  and  to  rob  the 
other  of  most  of  its  significance  in  the  consideration  of  modi- 
fication and  species-forming.  The  assumption  of  the  com- 
position of  germ-plasm  out  of  biophors  and  determinants 
is  of  course  merely  an  interesting  speculation,  or  tentative 
hypothesis,  which,  because  it  is  untestable  by  scientific  ob- 
servation or  experiment,  cannot  be  debated  to  any  particular 
advantage.  Weismann  himself,  in  1895,  definitely  conced- 
ing that  natural  selection  is  radically  weak  at  its  base,  being 
incapable  of  explaining  the  beginnings  of  useful  variations 
and  the  development  (which  actually  occurs)  of  indifferent 
ones,  proposed  a  new  and  radically  un-Darwinian  theory 
under  the  name  of  Germinal  Selection.  This  theory  (ex- 
plained in  chapter  viii  of  this  book)  although  including  the 


DARWINISM   DEFENDED.  135 

word  selection  in  its  name  is  fundamentally  different  from 
natural  selection  in  the  Darwinian  sense,  and  is  indeed 
an  admission  of  the  existence  of  variations  maintained  (not 
by  means  of  natural  selection)  along  definite  lines,  result- 
ing in  a  real  orthogenesis.  It  attempts  to  offer  a  causo- 
mechanical  explanation  of  such  un-Darwinian  development. 
By  the  theory  of  germinal  selection,  which  is  based  abso- 
lutely on  the  assumption  that  the  plasm  is  composed  of 
biophors  and  determinants  or  at  least  of  physical  life  units 
of  similar  type  and  function,  Weismann  hopes  to  strengthen 
four  weak  places  in  the  general  position  of  neo-Darwinism. 
The  theory  explains  (i)  how  in  Panmixia  (another  Weis- 
mannian  contribution  to  neo-Darwinism,  for  account  of 
which  see  chapter  viii)  the  degeneration  of  useless  organs 
is  brought  about,  (2)  how  it  is  that  for  the  continued 
development  of  any  certain  complex  adaptation  exactly  the 
right  variations  shall  appear  at  the  needed  time,  (3)  how  co- 
adaptation  comes  to  exist,  and  finally  (4)  how  variations 
may  come  to  be  developed  along  fixed  lines  or  in  definite 
directions  without  the  aid  of  personal  selection.  Whether 
the  theory  of  germinal  selection  explains  these  four  things 
or  not,  what  is  to  us  for  the  moment  the  chief  interest  of  the 
theory  is  that  it  is  put  forward  by  Weismann,  who  is  dis- 
tinctly the  foremost  nee-Darwinian,  to  explain  just  these 
things.  For  that  makes  of  these  things  concessions  that  the 
neo-Darwinians,  the  ultra-selectionists,  feel  forced  to  offer. 
It  should  be  noted,  however,  that  perhaps  Weismann  does 
not  speak  for  all  ultra-selectionists,  for  example,  Lloyd 
Morgan,  Ray  Lankester,  and  other  English  *  Darwinians. 
Certainly  his  theory  of  germinal  selection  is  accepted  by 
few  of  them. 

On  the  whole,  however,  I  think  I  speak  perfectly  fairly 
in  saying  that  the  believers  and  defenders  of  the  natural 
selection  theory  to-day  admit  in  large  measure  the  valid- 
ity of  those  criticisms  which  are  directed  at  the  inca- 


*36  DARWINISM   TO-DAY. 

pacity  of  Darwinism,  in  its  long  familiar  form,  to  account 
for  the  development  of  variations  and  modifications  up 
to  the  advantageous  or  disadvantageous  stage.  They  admit 
also  the  actual  existence,  and  in  abundant  measure,  of 
species  differences  which  are  of  indifferent  character,  that  is, 
of  no  especial  utility,  and  make  the  consequent  admission 
that  such  species  differences  cannot  for  the  most  part  be 
explained  by  natural  selection.  And  they  also  concede,  or 
at  least  most  of  them,  including  Weismann,  do,  the  force 
of  the  criticism  that  the  assumption  of  the  occurrence  of  the 
right  variations  at  the  right  time  is  a  necessity  for  the 
development  by  selection  of  many  if  not  most  specialisations 
of  qualitative  and  of  coadaptive  character,  which  assump- 
tion in  turn  demands  an  explanation  of  causes  anterior  to 
selection. 

And  finally  most  selectionists  concede  that  selection  can- 
not make  new  species  by  relying  on  the  extremes  of  series 
of  fluctuating  or  Darwinian  variations  because  of  the 
inevitable  extinguishing  or  swamping  of  these  extreme 
variations  by  inter-breeding  with  the  far  more  abundant 
average  or  modal  individuals  of  the  species.  Hence  all 
those  objections  recorded  in  the  chapters  on  "Darwin- 
ism Attacked"  which  have  to  do  solely  with  this  inca- 
pacity of  natural  selection  to  make  use  of  variations  too 
small  or  too  few  or  purely  fortuitous,  or  with  the  incapacity 
of  selection  to  explain  hosts  of  indifferent,  non-adaptive 
species  differences  which  actually  exist,  and  hence  with  the 
certainty  of  its  not  being  the  only  factor,  if  indeed  a  prin- 
cipal factor,  in  the  formation  of  species,  need  not  be  re- 
discussed,  at  least  to  any  length,  in  this  chapter.  We  may 
also  largely  neglect  those  objections  which  are  directed 
against  the  purely  hypothetical  assumptions  and  the  extreme 
positions  of  the  neo-Darwinians.  Many  of  these  assump- 
tions, such  as  that  of  the  absolute  isolation  and  independence 
from  the  soma  of  the  germ-plasm,  are  not  a  part  of  Dar- 


DARWINISM   DEFENDED.  137 

winism  proper,  and  the  extreme  position  of  the  believers  in 
the  Allmacht  of  selection  was  certainly  never  taken  by  Dar- 
win himself.  In  fact,  most  of  nee-Darwinism  has  been 
deserted  by  its  one-time  followers,  and  most  conspicuously 
and  perhaps  most  radically  by  Weismann  himself. 

Thus,  with  these  two  categories  of  objections  listed  in 

the  "Darwinism  Attacked"  chapter  put  to  one  side,  for  the 

moment  at  least,  by  admitting  the  validity  of  one  category 

and  showing  the  inapplicability  of  the  other  as  regards  its 

relation  to  true  Darwinism,  we  have  left  to  us 

The  objections  to  consider  those  remaining  objections  which. 

needing  answer, 

are  made  (i)  against  the  capability  of  selec- 
tion's making  any  use  at  all  of  the  familiar  and  always 
occurring  fluctuating  variations  called  Darwinian,  (2) 
against  its  capacity  to  explain  coadaptive  and  highly  com- 
plex adaptations,  especially  those  which  seem  as  if  they 
could  be  of  advantage  to  the  organism  only  in  fully 
developed  or  specialised  state,  (3)  against  its  inability  to 
account  for  overdeveloped  specialisations,  (4)  against  the 
possibility  of  selection's  explaining  qualitative  differences  in 
species,  and  many-branched  descent  (quantitative  differ- 
ences and  linear  descent  seeming  to  be  the  only  kinds  pos- 
sible to  it),  (5)  against  its  capacity  to  explain  complete 
or  extreme  structural  degeneration  of  useless  organs  and 
parts,  (6)  against  the  reality  and  extreme  rigour  of  the 
struggle  for  existence  and  personal  selection  (an  essential 
foundation  of  the  selection  theory),  (7)  against  the  sexual 
selection  theory,  particularly  in  its  capacity  as  a  supporting 
prop  of  the  natural  selection  theory,  (8)  against  the  reliance 
by  the  selectionists  on  the  homology  or  analogy  which  they 
hold  to  exist  between  natural  selection  and  artificial  selec- 
tion, and  finally  to  consider  those  curiously  positive  and 
definite  declarations  of  such  radical  anti-Darwinians  as 
Wolff,  Korschinsky,  and  others  that  natural  selection  is  a 
vagary,  having  no  claims  to  existence  either  on  a  basis  of 


*38  DARWINISM  TO-DAY. 

observation  or  logical  reasoning,  or  that  if  it  exists  its  whole 
influence  is  directly  inimical  to  changes  and  evolution  rather 
than  of  a  nature  to  produce  and  foster  them.  The  most 
comprehensive,  fairest,  and  most  effective  recent  attempt 
to  gather  together  and  meet  seriatim  the  objections  and 
criticisms  of  Darwinism  is  (as  already  stated  in  the  chapter 
on  "Darwinism  Attacked")  that  of  Ludwig  Plate,5  and  I 
have  therefore  given  considerable  space  in  this  chapter  to 
direct  quotations  from  the  answers  and  discussions  of  this 
modern  Darwinian  champion. 

The  objection  made  that  natural  selection  can  make  no  use 
at  all  of  the  small  fluctuating  Darwinian  variations  is  really 
Answer  to  the    a  w^er  application  of  the  really  valid  objection 
objection  that      that  such  variations  cannot,  or  can  only  rarely, 
offer  material  for  the  production  by  selection  of 


slight  to  be  of      new   organs    and   that    for   many   adaptations 

selective  value,      A  ,  ••   «^.  i  r 

they  are  too  slight  to  be  of  use  and  hence 
cannot  serve  as  handles  for  selection.  As  a  matter  of 
fact,  however,  many  adaptive  modifications  are  purely  quan- 
titative, not  necessarily  involving  any  qualitative  change 
at  all.  Increase  in  general  size,  or  in  any  one  dimension 
of  an  organ  or  part,  meaning  often  an  increase  of  strength 
on  the  part  of  the  animal,  in  the  capacity  for  aggres- 
sion or  defence,  in  swiftness,  in  flight,  running  or  swim- 
ming, in  reaching  or  digging  or  climbing  or  leaping  — 
such  an  adaptive  modification  might  well  be  brought  about 
by  selection  of  even  very  inconsiderable  enlargements  or 
strengthenings  of  one  or  more  organs  or  parts.  Wherever 
the  modification  is  in  a  directly  linear  path,  and  an  advantage 
is  possible  through  even  slight  advances  or  regressions  along 
this  line,  natural  selection  will  find  in  the  Darwinian  varia- 
tions a  means  of  fostering  and  perfecting  this  modification. 
There  are  just  two  requirements  necessary  for  the  Darwin- 
ian variations  to  meet  in  order  to  serve  as  handles  for 
natural  selection  :  they  must  be  variations  actually  suffi- 


DARWINISM   DEFENDED.  139 

ciently  useful  and  advantageous  to  turn  the  scale  in  the  intra- 
or  inter-specific  struggle  for  existence  in  favour  of  the 
individuals  possessing  them,  and  they  must  occur  in  suffi- 
ciently many  individuals  to  avoid  being  swamped  or 
extinguished  by  cross-breeding :  that  is,  they  must  be  useful 
enough  to  be  selected  and  numerous  enough  to  perpetuate 
themselves.  Do  Darwinian  variations  ever  meet  these  re- 
quirements ?  Unfortunately  our  proof  is  rather  indirect : 
observation  reveals  their  abundance,  but  does  not  actually 
show  their  utility.8  To  answer  the  question  our  judgment 
and  reason,  based  on  our  knowledge  and  experience  of  the 
existing  conditions  of  animal  and  plant  life,  will  have  to 
be  trusted  for  answer.  How  real  is  the  rigour;  how  keen 
the  struggle ;  how  crowded  the  square  yard  or  square  mile ; 
how  great  or  how  little  must  be  the  differences  in  a  part  to 
give  a  life-or-death  decision  in  the  competition?  Each 
naturalist  must  answer  this  for  himself,  and  the  layman 
must  take  the  general  consensus  of  opinion  of  the  natural- 
ists, if  there  is  one,  for  his  answer. 

The  objection  to  the  linear  and  quantitative  character  of 

the  Darwinian  variations  has  been  recently  especially  urged 

by  de  Vries  in  connection  with  his  exposition 

otyeTtion°con-      °*  the  tneorv  °f  species-forming  by  mutations. 

cemingthe         The  selection  theory  reckons  with  linear  hence 

linear  and  qnan-      .   «   . «  *^  . 

titative  charac-  strictly  quantitative  variations,  says  he,  and  yet 
ter  of  fluctuating  js  presumed  to  create  new  forms  for  which  in 

variation, 

reality  qualitative  variations  are  necessary  as 
a  basis,  so  that  in  fact  selection  can  only  increase  or 
diminish,  add  to  or  subtract  from  characters  already  in 
existence  and  cannot  create  anything  new,  this  appear- 
ance of  new  characteristics  being,  however,  precisely  the 
principal  peculiarity  of  new  species,  taken  by  and  large.  This 
position  of  de  Vries  has  been  discussed  by  Plate  T  as  follows : 
"I  call  attention  in  advance  to  the  fact  that  de  Vries 
understands  by  'linear  variations'  what  are  more  usually 


140  DARWINISM   TO-DAY. 

known  as  individual,  fluctuating  or  continuous  variations. 
He  has  chosen  this  name  because  the  single  characteristic 
can  change  toward  but  two  directions;  that  is,  toward  the 
plus,  or  toward  the  minus  direction.  In  contrast  to  this 
kind  of  variation  stand  the  sudden  and  discontinuous  leap- 
like  changes  or  mutations  which  have  been  for  the  first 
time  carefully  investigated  by  the  praiseworthy  labour  of 
de  Vries,  hitherto  having  been  familiar  indeed  under  the 
names  'single  variations'  or  'sports,'  but  little  studied.  Con- 
cerning these  linear  variations  de  Vries  writes :  The  statis- 
tical method  of  the  study  of  variation  has  now  been  so 
generally  followed  as  to  make  its  principles  familiar  without 
further  discussion,  and  they  may  be  considered  as  accepted. 
The  chief  principle  indicated  by  the  use  of  the  frequency 
curves  is  that  the  characteristics  vary  in  but  two  directions, 
that  is  toward  plus  or  toward  minus.  The  old  vague  con- 
ception of  an  all-sided  variation  of  the  single  characters 
has  disappeared  of  its  own  self.' 

"As  highly  as  I  appreciate  the  great  service  of  de  Vries 
in  relation  to  our  knowledge  of  the  suddenly  appearing 
changes,  heritable  in  high  degree,  I  must  nevertheless  op- 
pose him  in  his  conclusions  touching  the  selection  theory. 
In  the  first  place  this  theory  does  not  reckon  alone  with 
linear  variations,  but  also  with  mutations,  if  they  appear, 
for  it  takes  the  changes  as  given  material  without  troubling 
itself  about  differences  in  their  mode  of  origin.  In  the 
second  place  it  is  not  correct  that  a  character  cannot  so 
change  itself  through  simple  addition  or  reduction  that  it 
may  not  be,  in  the  customary  classificatory  limits,  looked  on 
as  a  new  character.  A  smooth  leaf,  a  leaf  with  few  small 
hairs,  and  one  with  a  thick  wool  show  only  linear  variations, 
but  in  spite  of  that  they  may  very  well  serve  as  character- 
istic of  different  species.  Nearly  related  butterflies — recall 
the  Vanessas  and  Lycsenas — often  show  the  same  funda- 
mental characters  of  pattern  and  form,  so  that  they  are  dis- 


DARWINISM   DEFENDED.  141 

tinguished  only  by  plus  or  minus  variations.  Indeed  one 
may  consider  the  whole  endless  manifoldness  of  organic 
combinations  as  only  representing  greater  or  lesser  num- 
bers of  atoms  of  the  same  few  elements  which  are  bound  to- 
gether in  one  molecule.  In  the  third  place  the  statistical 
studies  of  variation  have  not  shattered  in  any  respect  the 
conception  of  an  all-sided  variation  of  the  single  characters, 
but  indeed  on  the  contrary  have  rather  shown  that  all  the 
parts  and  attributes  of  organisms  that  are  accessible  to 
observation  appear  to  us  more  or  less  different  in  different 
individuals.  This  all-sided  variability  has  nothing  to  do 
with  the  statement  that  each  single  variable  element  can 
vary  always  only  toward  plus  or  toward  minus.  Blue 
flower  petals  can  appear  more  or  less  blue  and  at  the  same 
time  reveal  their  indeterminate,  fortuitous,  or  all-sided 
variability  in  differences  of  form,  hairiness,  thickness, 
structure,  etc.  The  same  indeterminateness  which  de  Vries 
claims  for  his  mutations  is  characteristic  also  of  linear 
variations." 

Tayler,8  a  Darwinian  defender,  has  discussed  this  objec- 
tion as  follows :  "This  objection  appears  to  me  to  be  one  of 
the  most  weighty  of  all  the  objections  which  have  been  raised 
to  the  selectional  hypothesis,  and  it  is  further  an  extremely 
difficult  objection  to  satisfactorily  reply  to;  first,  because  it  is 
almost  impossible  to  say  in  what  form  of  organism  the  earli- 
est variations  appeared,  and  without  this  no  judgment  on  the 
value  of  any  small  variation  can  be  of  use;  secondly,  it  is 
•equally  essential  to  know  the  kind  of  environment  which 
such  an  organism  was  living  in;  and  lastly,  if  we  were 
fully  acquainted  with  the  character  of  the  organism  and  its 
environment  it  would  still  be  difficult  to  form  any  adequate 
opinion  on  the  value  of  such  a  variation,  owing  to  the  fact 
that  this  apparently  simple  organism  would  differ  so  widely 
from  our  own  functional  activity  and  life  that  any  conclu- 
sions formed  on  comparative  methods  of  testing  its  powers, 


142  DARWINISM   TO-DAY. 

etc.,  would  be  extremely  likely  to  be  fallacious.  If,  however, 
we  keep  in  mind  the  facts  that  (  I  )  the  whole  and  not  merely 
a  part  of  the  organism  is  selected,,  and  that,  therefore, 
each  variation  does  not  require  to  be  of  the  same  value  as  if 
selection  depended  on  it  alone;  (2)  specialisations  are 
largely  quantitative,  between  man  at  one  extreme  of  de- 
velopment and  a  simple  unicellular  organism  at  the  other, 
the  difference,  though  very  great,  is  mainly  due  to  the  fact 
that  man  is  a  huge  multicellular  colony  ;  this  difficulty  will  be 
much  simplified.  To  estimate  the  quantitative  difference  it  is 
necessary  to  endeavour  to  determine  the  specialisation  of  an 
individual  cell  in  one  of  those  collective  specialisations  or 
organs  :  the  difference  between  a  cell  in,  for  instance,  the 
cerebral  cortex  of  man  and  the  character  of  an  amoeba  is  no 
doubt  great,  but  the  amceba  reacts  to  stimuli,  though  in  a 
less  specialised  form,  just  as  the  cortex  cell  does  ;  in  the  same 
way  the  reaction  to  light  in  the  mammalian  eye  is  not  a  new 
development  —  it  has  its  beginnings  in  the  preference  for 
light  or  darkness  shown  by  many  unicellular  organisms. 
These  two  points,  that  selection  is  organismal  and  that 
specialisations  are  as,  or  more,  largely  quantitative  than 
qualitative,  weaken  if  they  do  not  abolish  all  those  diffi- 
culties to  natural  selection  that  are  founded  on  this  objec- 
tion, and  it  is  further  necessary  to  recollect  that  no  specialisa- 
tion has  yet  been  found  which  has  not  a  primitive  counter- 
part in  the  earliest  known  forms  of  life." 

With  regard  to  the  objection  that  because  natural  selec- 
tion   working    with    fluctuating    Darwinian    variations    is 
working  only  with  linear  or  quantitative  varia- 

tionS     an(*     there^ore     Cannot     produce     many- 
selection  cannot    branched  descent   (which  is  certainly  the  kind 
of  descent  that  exists)  but  only  straight-line  or 


and  discontinuity  mono-typic  descent,  it  is  obvious  that  the  Dar- 

winian  answer  to  this   is   partly   that   of  the 

answer  to  the  objection  discussed  in  the  last  paragraph.    In 


DARWINISM   DEFENDED.  143 

addition  it  is  partly  that  of  the  answer  to  the  objection  to 
be  mentioned  in  the  next  sentence.  This  related  objection 
is  that  while  natural  selection  may  produce  continuous 
gradatory  adaptive  change  or  evolution  it  cannot  produce 
discontinuity  in  the  series,  i.  e.,  cannot  produce  separated 
distinct  species.  This  objection  receives  an  answer  which 
is  of  the  nature  of  an  admission  that  natural  selection  wholly 
unaided  really  cannot  differentiate  species.  It  must  call  to 
its  aid  some  isolation  or  segregation  factor,  and  as  isolation 
is  certainly  most  commonly  effected  through  migration  and 
geographic  means,  it  is  usually  this  factor  of  geographic 
isolation  that  natural  selection  must  be  accompanied  by  to 
form  new  species.  As  Plate  says :  "Any  particular  phase 
of  the  struggle  for  existence  extinguishes  all  those  indi- 
viduals which  do  not  possess  certain  absolutely  necessary 
characteristics.  By  this  means  there  is  produced  a  common 
type.  And  only  when  some  means  of  isolation  is  added  can 
the  splitting  of  the  species  into  two  or  more  forms  result. 
Natural  selection  can  only  transform  a  species  gradually 
and  develop  it  in  a  continuous  forthright  line ;  alone  it  cannot 
produce  a  divergent,  tree-like  evolution.  This  results  from 
geographic,  biologic,  or  sexual  isolation,  which  is  in  most 
cases  a  form  of  the  extensive  manner  of  working  of  the 
struggle  for  existence.  But  selection  can  aid  in  the  differ- 
entiation of  a  species  into  two  or  more  forms,  as  the  following 
examples  show.  When  all  average  or  median-sized  in- 
dividuals of  a  species  are  killed  out  there  remain  only  the 
smallest  and  the  largest,  by  which  we  may  assume  that  the 
first  are  saved  because  they  can  most  readily  conceal  them- 
selves, while  the  latter  find  in  their  great  size  a  sufficient 
protection.  On  the  ground  of  this  difference  in  size  perhaps 
both  forms  will  be  inclined  to  keep  apart  from  each  other 
and  if  to  this  is  added  a  somewhat  differing  habit  of  life, 
two  races  can  arise  which  in  course  of  time  will  become 
distinct  species.  From  a  butterfly  kind  of  very  variable 


144  DARWINISM   TO-DAY. 

•colour-tone  all  brown  individuals  might  disappear  for  some 
special  reason  while  both  the  lighter  and  darker  individuals 
might  persist.  Now  if  in  consequence  of  this  contrast  a 
racial  feeling  should  develop  between  the  light  individuals 
on  the  one  hand  and  the  dark  ones  on  the  other,  the  differ- 
entiation into  two  species  is  already  begun.  If  a  snail  species 
living  in  fresh  water  is  so  harassed  that  it  can  only  maintain 
itself  when  its  individuals  move  either  into  the  region  be- 
tween tide-lines  or  into  the  deeper  water,  this  would  lead  to 
morphological  differentiation,  as  we  can  indeed  actually  note 
in  the  case  of  the  chitons." 

The  objection  that  the  existence  of  coadaptive  and  highly 

complex  adaptations,  especially  those  which  seem  as  if  they 

could  be  of  no  possible  advantage  to  their  pos- 

Answer  to  the    sessors  except  in  their  present  fully  developed 
objection  con-  .   ,.       ,  .  .  . 

ceming  complex  or  specialised  state,  is  one  which  unfortunately 


cannot  be  definitely  refuted  or  proved  by  ever 
so  much  ingenious  explaining  or  discussion  in 
the  face  of  the  lack  of  what  we  certainly  do  not  now 
possess,  namely,  direct  observational  or  experimental  evi- 
dence. For  such  specialisations  as  elaborate  mimickry,  or 
the  electric  organ  of  the  torpedo,  etc.,  which  are  of  appa- 
rent advantage  only  in  perfected  state,  the  selectionist  is 
forced  to  admit  that  the  objector  has  apparently  a  good  case, 
tut  for  the  gradual  specialisation  of  many  highly  complex 
structures  and  specialisations  through  the  long-continued 
selection  of  slight  advantageous  variations,  Darwin  and  his 
followers  have  offered  ingenious  and  plausible  explanations. 
For  the  case  of  so  complex  and  coadaptive  a  specialisation  as 
the  eye  and  its  function  in  the  vertebrates  or  in  the  insects 
and  crustaceans,  the  possible  evolution,  by  slight  additions 
and  modifications,  from  simple  pigment  fleck  to  the  present 
marvellous  visual  organ,  a  logically  irrefutable  Darwinian 
argument  can  be  made  out  on  the  basis  of  the  real  and 
constant  utility  and  advantage  of  even  very  slight  steps 


DARWINISM   DEFENDED.  145 

forward.  And  so  with  many  other  complex  specialisations, 
although  in  almost  all  these  cases  it  is  necessary,  as  Darwin 
says,  to  let  the  reason  conquer  the  imagination.  That  is,  the 
reasoned  explanation  explains,  although  one  recoils  con- 
stantly before  the  almost  inconceivable  actuality  of  the 
phenomenon. 

Plate  has  recognised  this  objection  as  one  of  the  really 
weighty  ones  and  has  given  much  attention  to  its  considera- 
tion. His  conclusion  is  that  it  is  necessary  to  rely  to  a 
greater  or  less  extent  on  the  Lamarckian  factor  of  the 
inheritance  of  somatogenic  characters  acquired  in  the  life- 
time of  the  individual  through  the  effects  of  use,  or  disuse, 
or  other  functional  stimuli.  This  is,  of  course,  direct  aban- 
donment of  the  position  maintained  by  such  strict  selection- 
ists as  Weismann  and  Wallace,  although  Weismann  himself, 
in  order  to  answer  the  objection  without  having  recourse 
to  reliance  on  Lamarckian  factors,  introduces  his  new 
theory  or  hypothesis  of  germinal  selection  to  aid  natural 
selection  in  the  difficulty  presented  by  the  objection.  Lloyd 
Morgan's  9  answer  to  this  objection  consists  chiefly  of  the 
formulation  of  the  theory  of  orthoplasy  (explained  in  chapter 
viii  of  this  book).  It  is,  briefly,  that  every  organism,  from 
its  somatic  and  germinal  aspects,  exhibits  two  tendencies 
of  variability.  The  somatic  variability  is  determined  largely 
or  at  least  modified  largely  by  environmental  influences ; 
therefore  those  organisms  whose  somatic  tendency  is  pre- 
dominantly plastic  will  survive  under  altered  conditions  of 
environment,  where  those  organisms  of  a  less  easily  mod- 
ifiable tendency  will  be  eliminated.  Now  if  somatic  changes 
rarely  or  never  become  germinal,  i.e.,  are  inherited,  the  mod- 
ifications of  the  parental  organisms  cannot  be  transmitted 
to  their  offspring,  but  those  offspring  that  happen  to  be 
endowed  with  germinal  variations  in  the  same  direction 
as  the  acquired  but  not  transmitted  modifications  would 
start  their  life  with  a  predisposition  favourable  to  their 


146  DARWINISM   TO-DAY. 

environment  and  therefore  favourable  to  more  complete 
modification  of  the  somatic  side  of  the  organism ;  this  tend- 
ency being  accumulative  under  constant  conditions,  coinci- 
dent variability  would  arise  by  the  process  of  selective 
elimination  and  preservation,  without  the  need  of  the 
assumption  of  use-inheritance,  which  assumption  facts 
appear  to  negative. 

Against  the  criticism  that  natural  selection  cannot  explain 

over-developments   of   specialisation,   that  is,   the  carrying 

unnecessarily   far   of   advantageous    structural 

objection1  con-  *   an^   functional  development,  as  illustrated  by 

cemingover-  the  great  antlers  of  stags  and  moose,  the  micro- 
specialisation,  •!•««•  F  '  •  • 

scopic  fidelity  of  simulation  and  mimicry,  and 
the  nearly  identical  equivalence  of  the  right  and  left  halves 
of  bilaterally  symmetrical  animals,  the  selectionist  has  little 
to  offer  except  the  always  pertinent  questions :  Are  we  sure 
that  the  case  in  point  is  one  of  over-development,  of  unnec- 
essary specialisation?  And  although  the  palseo-zoologists 
may  be  pretty  emphatic  in  their  declarations  that  the  ex- 
tinction of  the  Irish  stag  and  of  the  unwieldy  cretaceous 
reptiles  was  directly  due  to  over-specialisation,  they  cannot 
prove  it.  And  there  you  are,  says  the  Darwinist. 

The  difficulty  that  natural  selection  has  with  structural 
degeneration  is  admittedly  a  real  one.    The  strict  Darwinian- 
answer  has  to  be  that  retrogression  is  produced 
of  the^bjection    either  by  reversed  selection,  that  is,  that  when 
concerning  de-     by  a  change  in  the  life  habits  or  external  condi- 

generation,  .  ....  .    . 

tions  a  certain  function  or  organ  becomes  inju- 
rious, as  in  the  case  of  insects  on  small  exposed  islands 
where  the  wind  might  carry  the  flying  ones  off  into  the 
ocean,  selection,  on  the  basis  of  advantage,  would  tend  to 
preserve  the  ones  most  poorly  equipped  for  flight;  or  it 
has  to  be  that  when  the  function  of  an  organ  is,  because  of 
change  in  habit  or  conditions,  once  neglected  or  discon- 
tinued, that  is,  the  organ  is  no  longer  used,  any  slight  varia- 


DARWINISM    DEFENDED.  147 

tion  toward  reduction  of  the  organ  would  be  of  advantage 
because  of  the  saving  in  food  which  would  be  effected !  But 
this  is  simply  carrying  the  logic  of  the  principle  of  advan- 
tage to  an  illogical  extreme,  an  extreme  impossible  to  accept. 
So  Weismann  devised  the  ingenious  explanation  of  pan- 
mixia or  cessation  of  selection  to  account  for  degeneration. 
That  is,  a  rigid  and  persistent  selective  activity  is  as  neces- 
sary to  maintain  a  specialisation  as  it  was  to  produce  it. 
But  even  Weismann  has  found  this  explanation  inadequate 
and  has,  therefore,  found  a  final  and  sufficient  explanation 
in  his  new  theory  of  germinal  selection.  This  last  theory,  a 
refinement  of  Roux's  theory  of  the  battle  of  the  parts,  is 
ingenious,  suggestive,  and  thoroughly  interesting,  but  un- 
fortunately it  is  founded  on  certain  assumptions  concerning 
the  ultimate  make-up  of  the  germ-plasm  and  the  behaviour 
of  the  unit  parts  of  it,  the  truth  of  which  simply  cannot  be 
tested.  A  strictly  neo-Darwinian  answer,  that  is,  one  based 
solely  on  selection,  is  therefore  hard  to  give.  Plate,10  after 
an  effective  adverse  criticism  of  the  influence  of  the  Weis- 
mannian  panmixia  as  an  explanation  of  the  structural  reduc- 
tion or  atrophy  of  parts,  concludes  that  such  reduced  or 
rudimentary  organs  are  to  be  explained  "through  the 
inherited  effects  of  disuse,  the  inherited  effects  of  the  influ- 
ences of  external  factors,  the  inherited  effects  of  the  influence 
of  economy  in  nutrition,  and,  in  a  few  cases,  through  re- 
versed selection.  The  first  three  principles  are  only  admissi- 
ble under  the  assumption  of  the  actuality  of  the  inheritance 
of  individually  acquired  characters,  and  the  fourth  principle 
has  only  a  very  subordinate  importance."  This  is  equivalent 
to  saying  that  the  strict  selectionist  has  no  sufficient  answer 
to  the  objection  under  present  consideration.  One  seems 
forced  to  rely  on  Lamarckian  factors  for  anything  like  a 
satisfactory  explanation  of  actual  structural  reduction  of 
useless  organs.  Tayler,11  however,  offers  an  explanation 
for  both  ontogenic  and  phyletic  degeneration,  based  on  the 


148  DARWINISM   TO-DAY. 

"known  facts  of  nutrition."    The  interested  reader  may  find 
this  explanation  in  the  appendix  to  this  chapter. 

Doubt  is  expressed  by  some  biologists  of  the  reality  and 
fierceness  of  the  struggle  for  existence  which  is  an  essential 
part   of   the   selection   theory.      De   Vries    ex- 
presses  the  belief  that  the  intra-specific  strug- 


against  the  rig-    gle,  that  is,  the  struggle  and  competition  among 

our  of  selection.     '        .    .  p  .  , 

individuals  of  the  same  species,  has  been  much 
overrated.  And  a  few  observations  12  have  actually  been 
made  which  indicate  that  for  certain  species  this  struggle 
is  at  least  not  rigorous  enough  to  give  to  the  slight  Dar- 
winian variations  a  determining  value  as  to  the  character 
of  the  surviving  individuals.  Here  again  the  proof  for  the 
Darwinian  point  of  view  is  not  one  so  much  of  observa- 
tion —  although  actual  life-and-death  combats  between  indi- 
viduals of  a  single  species,  and  innumerable  examples  of 
the  preying  of  one  species  on  another  are  familiar  —  as  it  is 
a  proof  of  reasoning.  The  fact  of  an  over-production  of 
eggs  and  embryos,  that  is,  of  reproduction  by  multiplica- 
tion, is  undeniable.  The  lack  of  existing  space  and  food 
for  all  individuals,  if  all  should  live  the  ordinary  span  of 
life  peculiar  to  the  species,  is  demonstrable  by  mathematics. 
The  consequent  conclusion  of  these  two  established  premises 
is  a  struggle  for  existence.  That  is  the  sound  Darwinian 
position. 

The  principal  answer  of  the  Darwinians  to  the  criticisms 
levelled  at  the  theory  of  sexual  selection  is,  that  however 

ineffective  the  theory  is  to  explain  many  of  the 
objections  to  the  phenomena  it  is  called  on  to  cover,  it  is  at  least 
sexual  selection  so  much  more  reasonable  and  satisfying  as  an 

explanation  of  some  of  the  phenomena,  that  is, 
some  of  the  categories  of  secondary  sexual  characters,  such 
as  the  ornamental  plumes  and  colour-patterns  of  birds,  the 
sound-making  organs  of  insects,  etc.,  than  any  alternative 
explanation  that  has  been  offered,  that  until  a  better  expla- 


DARWINISM   DEFENDED.  149 

nation  be  presented  the  theory  of  sexual  selection  should 
not  be  discarded.  That  no  other  explanation  of  many,  if  not 
most,  of  the  phenomena  in  question  has  anything  at  all 
convincing  or  satisfactory  about  it,  or  has  met  with  any 
general  acceptance  on  the  part  of  naturalists,  is  the  plain 
truth.  If  we  feel  it  imperative  to  give  our  adherence,  with 
certain  reservations,  to  any  explanatory  hypothesis  of  sec- 
ondary sexual  characters,  Darwin's  theory  is  the  one  to 
have  first  claim  on  us.  As  a  matter  of  personal  opinion  I 
feel  no  necessity  for  any  such  attitude  and  am  willing  to 
look  on  most  of  the  phenomena  connected  with  the  general 
problem  of  secondary  sexual  characters  as  quite  inexplica- 
ble on  the  basis  of  our  present  knowledge  of  bionomics. 

The  specific  answer  of  Lloyd  Morgan  13  and  other  Dar- 
winians to  the  objection  that  choice  on  the  part  of  the 
female  assumes  an  aesthetic  recognition  and  preference 
which  it  is  doing  violence  to  our  knowledge  of  animal 
psychology  to  assume,  should  not  be  overlooked.  This 
answer  is,  put  summarily,  that  this  so-called  choice  is  one 
of  impulse,  not  deliberation :  it  is  an  imperative  reaction  to 
a  sufficient  stimulus :  and  what  determines  that  the  stimulus 
from  one  male  shall  be  sufficient  while  that  from  another  is 
not,  is  the  degree  of  pronouncedness  or  effectiveness  of  the 
ornament,  or  call,  or  behaviour.  It  is  a  choice  "which  is 
determined  by  the  emotional  meaning  of  the  conscious  mean- 
ing. And  it  is  the  reiterated  revival  of  the  associated 
emotional  elements  which  generates  an  impulse  sufficiently 
strong  to  overcome  her  instinctive  coyness  and  reluctance. 
...  It  is  a  perceptual  choice  arising  from  impulse  rather 
than  an  ideational  choice  due  to  motive  and  volition." 

Regarding  Wolff's  argument  that  an  explanation  of  these 
characters  is  very  necessary  to  the  acceptance  of  the  theory 
of  natural  selection  there  is  little  to  say  in  rebuttal.  Natural 
selection  confesses  itself  inadequate  to  explain  those  ex- 
traordinary characters  and  conditions  by  which  the  males 


150  DARWINISM   TO-DAY. 

of  many  species  of  mammals,  birds,  insects,  spiders,  etc., 
differ  from  the  females.  And  if  sexual  selection  does  not 
explain  them  then  some  other  explanation  is  necessary.  But 
the  lack  of  this  explanation  does  not  invalidate  the  general 
theory  of  natural  selection  as  one  of  the  factors  in  organic 
evolution  and  indeed  one  of  the  most  important  and  far- 
reaching  ones. 

The  difficulty  of  a  satisfactory  discussion  of  the  objection 

that  natural  selection  rests  too  largely  on  an  assumed  likeness 

to  artificial  selection,  while  the  differences  in 

Consideration    ^he  two  processes,  especially  in  their  results,  are 

of  the  objection  * 

that  natural  se-    too  radical  to  allow  us  to  rest  any  confidence 


on  this  aPParent  homology,  is,  that  despite  the 
assumed  analogy  several  thousand  years  through  which  artificial 
selection  Cla  selection  has  been  followed  and  studied  we 

still  know  too  little  of  the  real  character  of  it, 
especially  of  its  results.  Most  selectionists  now  admit  that 
the  argument  for  natural  selection  on  the  basis  of  its  sim- 
ilarity to  artificial  selection  has  been  given  too  great  promi- 
nence and  relied  on  too  strongly,  but  that  the  observed 
processes  of  the  one  do  teach  us  much  of  truth  about  the 
unobservable  processes  of  the  other  the  Darwinians  firmly 
maintain.  As  Plate  says,  "The  great  value  of  artificial 
selection  consists  in  this,  that  it  shows  first,  that  a  gradual 
cumulation  of  characteristics  in  definite  directions  is  actually 
possible  through  successive  selections,  and  second,  that  it 
has  afforded  us  a  rich  mass  of  data  concerning  variation, 
inheritance,  and  the  influence  of  changing  intrinsic  condi- 
tions or  influences.  When  Darwin  showed  what  a  high 
plasticity  the  domestic  animals  possess  he  built  for  his 
theoretical  explanation  of  descent  an  indubitable  necessary 
foundation,  for  the  changes  which  a  domestic  animal  passes 
through  in  the  hands  of  man  must  of  necessity  be  able  to 
be  called  forth  in  similar  manner  in  the  feral  animals  by 
the  creative  force  of  nature,  for  the  domestic  animals  cer- 


DARWINISM   DEFENDED.  151 

tainly  have  come  from  the  wild  ones.  It  is  also  true  that 
man  has  made  use  of  only  natural  factors,  and  whoever  will 
compare  the  extraordinary  creatures  of  the  deep  sea  with 
even  the  most  bizarre  of  our  cultivated  races,  will  see  that 
the  fluxing  life-conditions  of  free  nature  can  modify  or 
reform  the  animal  world  in  no  less  degree  than  the  intelli- 
gence of  man  can  do  it.  ... 

"Recently  de  Vries,14  in  his  book  on  'Mutations,'  has  tried 
to  deny  the  worth  of  the  selection  principle,  and  although 
I  fully  recognise  the  high  worth  of  his  contribution  to  science 
based  on  such  extensive  series  of  experiments,  yet  I  must 
oppose  him  in  this  position.  In  various  places  in  the  book 
he  writes  that  nothing  fixed  can  be  produced  by  selection, 
and  that  therefore  it  can  have  no  importance  as  a  working 
factor  in  descent.  For  example,  in  the  introduction  (p.  6) 
he  says :  'Artificial  selection  never,  as  far  as  experience 
reaches,  leads  to  the  origin  of  new  complete  types.'  The 
reversion  of  modified  domesticated  races  is  indubitable,  and 
de  Vries  himself  has  brought  forward  new  illustrations  of 
this  fact  which  has  been  so  long  known.  But  convincing 
proof  that  natural  selection  cannot  lead  to  constant  forms 
cannot  be  deduced  from  these  observations,  because  they 
refer  in  all  cases  to  forms  which  have  been  highly  modified 
in  the  course  of  a  few  years  or  decades,  so  that  the  pre- 
sumption lies  close  at  hand  that  there  has  not  been  sufficient 
time  really  and  lastingly  to  modify  the  original  heredity 
established  by  centuries.  Many  facts  indicate  that  the  in- 
tensity of  heredity  depends  upon  the  number  of  generations, 
that  is,  upon  time.  Long-inherited  characters  are  difficult 
to  eradicate;  recent  ones  easy.  We  can,  therefore,  not 
expect  to  meet  such  a  constancy  in  the  products  of  a  century 
as  we  find  in  Nature.  Many  gradually  selected  races  of 
doves  are  now  almost  entirely  constant,  that  is,  no  longer 
revert  to  the  primitive  race  when  they  are  inter-bred.  The 
way  in  which  the  reversions  appear  shows  that  the  duration 


152  DARWINISM   TO-DAY. 

of  time  plays  an  important  role  in  inheritance  (heredity). 
Schubeler  found  in  his  studies  of  the  translation  of  the 
northern  boundary  of  the  grain  culture  that  the  characters 
newly  acquired  (heavier  and  earlier  ripening  seeds)  per- 
sisted for  several  generations  when  the  forms  were  replanted 
in  the  original  [more  southerly]  habitat.  De  Vries  in  six 
years  selected  corn  which  had  an  average  of  20  rows  of 
kernels  instead  of  the  original  12  to  14,  and  held  the  plants 
at  this  height  of  production  through  five  years.  When  he 
then  planted  seed  from  a  i6-rowed  ear,  the  average  of  the 
ears  gathered  from  this  planting  was  in  the  first  generation 
still  at  20  rows,  and  sank  only  in  the  next  two  years  again 
to  14  to  16.  If  he  had  continued  his  selection  longer  he 
would  have  arrived  at  a  more  nearly  constant  form.  De 
Vries  himself  says:  'When  the  selection  ceases,  the  selected 
characteristics  drop  away  and  in  practically  the  same  length 
of  time  which  was  necessary  for  the  production  of  the  new 
race,  that  is  within  a  few  generations.'  From  this  it  follows 
that  a  domestic  race  produced  by  slow  persistent  selection 
through  many  thousands  of  generations  would  show  the 
same  relative  constancy  or  fixity  as  natural  species,  the 
majority  of  which  also  must  have  originated  slowly,  for 
otherwise  the  appearance  of  new  species  would  be  often 
observed.  If  one  wishes  to  be  very  conservative  in  this 
matter  one  may  declare :  in  the  light  of  our  present  knowl- 
edge we  cannot  say  that  artificial  selection  gives  us  any  safe 
means  of  judging  just  what  degree  of  constancy  [fixity]  can 
be  attained  by  its  means ;  but  it  is  not  fair  to  say  that  be- 
cause up  to  the  present  only  a  partial  constancy  has  been 
reached  through  artificial  selection,  natural  selection  cannot 
have  led  to  the  production  of  constant  species.  All  culti- 
vated races  have  been  relatively  quickly,  some  indeed  very 
quickly,  selected 15  and,  therefore,  they  strike  back  very 
quickly.  This,  however,  need  not  be  assumed  for  the  slowly 
arisen  products  of  natural  selection." 


DARWINISM   DEFENDED.  153 

Tayler,1'  making  a  general  defence  of  the  natural  selection 

theory,  says :  "To  realise  how  far  the  theory  of  selection  is 

capable  of  explaining:  the  facts  of  organic  evo- 

Tayler's  gen- 

oral  defense  of  lution,  it  is  necessary  to  bear  m  mind  the 
natural  selection,  pOstulates  on  which  the  theory  is  founded. 

"i.  It  is  obvious  that  natural  selection  can  only  act  by 
preserving  or  eliminating  the  complete  organism.  Selection 
must  therefore  be  organismal.  This  Darwin  and  other 
selectionists  have  clearly  recognised. 

"2.  As  the  whole  organism  must  survive,  if  the  favoura- 
ble variation  or  variations  are  to  be  preserved,  it  follows  that 
certain  minor  unfavourable  variations  may  also  be  pre- 
served if  they  happen  to  exist  in  an  individual  which  sur- 
vives on  account  of  its  major  favourable  variations.  And 
since  no  individual  is  completely  adapted  to.  its  environment, 
it  follows  that  there  must  be  always  a  variable  amount  of 
residual  unfavourable  variability  in  every  organism. 

"3.  This  residual  unfavourable  variability  may  be  of  con- 
siderable utility  under  changed  conditions. 

"4.  Complementary  specialisation  of  parts,  as  Spencer 
has  shown,  is  favourable  to  successful  competition,  and  as  it 
is  the  whole  organism  that  is  selected  or  eliminated,  it  fol- 
lows that  any  weakness  of  one  specialised  part,  since  it  would 
disturb  the  balance  of  all,  would  be  detrimental.  The  more 
complex  the  organism,  the  more  specialised  the  structures, 
the  more  dependent  one  part  will  be  on  the  others  for  its 
existence,  hence  a  complementary  specialising  tendency  will 
be  favoured  by  selection,  and  therefore  all  struggles  of  one 
part  of  an  organism  with  another  will  be  reduced  to  a 
minimum. 

"It  is  clear  that  there  must  be  some  underlying  criterion 
which  determines  whether  any  given  organism  shall  be 
selected  or  not,  and  that  criterion  must  be  the  net  result  of 
its  adaptability  to  its  environment.  One  organism  may  con- 
ceivably survive,  by  its  possession  of  a  large  number  of  small 


154  DARWINISM    TO-DAY. 

favourable  variations,  while  another  may  survive  in  virtue 
•of  a  single  valuable  one,  but  in  each  case  it  would  be  the 
whole  value  of  that  organism  which  determined  its  survival. 
This  fact  is  continually  disregarded  by  opponents  of  the 
neo-Darwinian  position,  yet  this  selection  of  the  organism 
as  a  whole  is  the  fundamental  postulate  from  which  the 
theory  of  selection  starts.  Thus  it  is  not  uncommon  to 
read  criticisms  bearing  on  the  early  development  of  some 
organ,  in  which  the  inadequacy  of  selection  is  supposed  to 
be  proved  by  the  writer  demonstrating,  or  believing  he  has 
demonstrated,  the  fact  that  the  particular  variation  in  ques- 
tion must  have  been  too  small  to  be  by  itself  of  selection 
value.  In  many  cases  the  particular  variation  would,  no 
doubt,  if  taken  alone  be,  as  the  objector  asserts,  too  unim- 
portant to  be  selected,  but  as  it  is  the  whole  organism  that 
is  selected,  it  is  not  logical  to  make  an  artificial  separation 
and  study  the  development  of  one  organ  or  structure  irre- 
spective of  the  other  organs  with  which  it  is  in  nature  asso- 
ciated. Every  organ  in  its  evolution  must  be  considered  in 
relation  to  the  whole  of  the  particular  organism  in  which 
that  particular  stage  of  development  of  that  organ  is  found. 
Starting,  therefore,  with  this  fact  that  the  net  value  of 
adaptability  of  the  whole  organism  to  its  environment  must 
be  the  basis  which  determines  selection  or  elimination,  it 
will  follow  that  certain  lines  of  development  will  result  from 
the  application  of  this  criterion.  In  a  series  of  organisms 
placed  under  new  conditions,  elimination  will  proceed  along 
lines  essential  to  bring  about  a  proper  adjustment  to  the 
new  conditions.  If  the  offspring  of  these  adjusted  organ- 
isms merely  repeated  in  their  generation  the  characters  of 
the  exterminated  as  well  as  of  the  surviving  organisms, 
that  temporary  adjustment  would  be  permanent  as  long  as 
the  conditions  were  unchanged.  But  since  the  offspring  are 
produced  only  by  the  surviving  organisms,  selection  is  con- 
tinually raised  to  higher  and  higher  planes  of  adaptation, 


DARWINISM   DEFENDED.  155 

and,  therefore,  as  long  as  conditions  remain  constant,  the 
tendency  of  selection  must  be,  as  Darwin  clearly  saw,  cumu- 
lative. He  did  not,  however,  apparently  see  that  from  this 
cumulative  tendency  definite  variability  must  arise  out  of 
indefinite. 

"Selection  in  direct  relation  to  climatic  conditions  is,  there- 
fore, of  very  minor  importance,  while  selection  among  the 
members  of  a  species  and  all  forms  of  inter-organismal 
selection  is  of  infinitely  more  importance,  since  it  is  this 
interaction,  produced  by  the  offspring  in  different  degrees 
inheriting  the  advantages  of  both  parents  (both  of  whom 
have  survived  on  account  of  certain  advantages),  that  leads 
to  the  cumulative  development  and  never-ending  struggle 
for  survival.  Darwin  came  very  near  to  this  conception  of 
definite  variability  when  he  pointed  out  that  'if  a  country 
were  changing  the  altered  conditions  would  tend  to  cause 
variation,  not  but  what  I  believe  most  beings  vary  at  all 
times  enough  for  selection  to  act  on.'  Extermination  would 
expose  the  remainder  to  'the  mutual  action  of  a  different 
set  of  inhabitants,  which  I  believe  to  be  more  important  to 
the  life  of  each  being  than  mere  climate,'  *  and  as  'the  same 
spot  will  support  more  life  if  occupied  by  very  diverse 
forms,'  it  is  evident  that  selection  will  favour  very  great 
diversity  of  structure. 

"Bearing  in  mind  this  cumulative  action  of  selection  it 
will  follow  that  under  constant  or  relatively  constant  con- 
ditions the  struggle  for  successful  living  will  become  more 
and  more  selective  in  character,  even  if  the  actual  number 
of  inhabitants  remain  more  or  less  the  same  as  when  the 
struggle  first  commenced.  The  selection  of  variations  will 
thus  tend  to  pass  through  certain  more  or  less  ill-defined, 
but  nevertheless,  real  stages.  In  proportion  as  the  struggle 
becomes  intense,  either  from  the  number  or  from  the  in- 

*From  Poulton's  "Charles  Darwin  and  the  Theory  of  Natural 
Selection"  (Abstract  of  Darwin's  letter  to  Professor  Asa  Gray). 


156  DARWINISM   TO-DAY. 

creasing  adaptability  of  the  organisms,  or  both,  certain 
major  essential  adaptations,  which  were  necessary  for  the 
climatic  and  other  more  or  less  comparatively  simple  con- 
ditions, will  be  supplemented  by  minor  auxiliary  variations 
which  in  the  earlier  stages  would  not  have  appeared.  And 
still  later,  as  more  and  more  rigorous  conditions  of  life  were 
imposed,  the  advantage  would  tend  to  rest  with  those  organ- 
isms which  possessed  highly  coordinated  adaptations,  since 
this  would  entail  more  rapid  responsiveness  to  environment. 
"As  evolution  advances  from  the  unspecialised  to  the  spe- 
cialised, and  higher  and  higher  forms  of  life  come  into 
being,  with  increasing  complexity  and  specialisation  of  parts 
entailing  an  increasingly  delicate  adjustment  of  those  parts 
to  each  other's  needs,  the  relation  of  each  part  to  the  whole 
organism  becomes  of  more  and  more  importance,  and  it 
follows  that  selection  must  become  more  and  more  general- 
ised in  its  action.  No  single  variation  could  be  of  service 
to  any  of  the  higher  forms  of  life  unless  it  was  in  more  or 
less  complete  harmony  with  the  whole  tendency  of  the 
individual.  The  adjustment  of  parts  and  their  mutual  inter- 
dependence make  it  essential  for  adaptation  that  the  relation 
of  parts  be  preserved;  consequently,  correlated  minute 
favourable  variations  will  tend  to  be  more  and  more  selected 
as  evolution  passes  from  the  unspecialised  to  the  specialised 
forms  of  life.  This  response  of  the  whole  organism  should 
be  still  more  delicate  in  those  forms  of  life  that  are  con- 
tinually subjecting  themselves  to  changed  conditions;  hence 
this  delicacy  of  adjustment  is  far  more  necessary  in  the 
higher  forms  of  animal  life  than  in  the  more  stationary  plant 
organisms,  and  in  the  developing  nervous  system  of  animals 
we  have  just  the  central  adjusting  system  that  is  required  for 
these  conditions.  With  evolution  of  type  there  will  thus  be 
an  increasingly  definite  tendency  given  to  organic,  espe- 
cially the  animal,  forms  of  life,  if  the  acting  principle  of 
evolution  has  been  selectional.  Selection  is,  therefore,  able 


DARWINISM   DEFENDED.  157 

to  account  for  the  steadily  progressive  tendency  of  life  as  a 
whole  without  calling  to  its  aid  any  unknown  and  doubtful 
perfecting  principle. 

"To  summarise : — Natural  selection,  acting  on  the  whole 
organism,  tends  to  produce  more  and  more  definite  tend- 
encies in  all  surviving  forms  of  life,  which  tendencies  are 
progressive  and  continuous  in  character.  Variable  condi- 
tions, by  partially  altering  the  line  of  selection,  induce  a 
temporary  indefiniteness.  And  lastly,  the  process  of  selec- 
tion being  itself  able  to  be  the  indirect,  though  not  the  direct, 
cause  of  those  favourable  variations,  which  it  subsequently 
selects  from,  is  able  to  dispense  with  any  subsidiary  factors, 
provided  it  has  a  certain  number  of  elementary  properties 
of  life  which  afford  sufficient  material  to  work  with." 


APPENDIX. 

1  Semper,  Carl,  "Der  Haeckelismus  in  der  Zoologie,"  1876. 

2  In    1876,    Gustav    Jaeger    anticipated    Weismann's    later    much- 
heralded    theory    of    the    continuity    of    the    germ-plasm    in    his 
"Zoologische  Briefen." 

3  For  an   excellent  detailed  critical  account  of  these  general,  as 
well  as  the   several  accessory  theories    (amphimixis,  polar  bodies, 
etc.)  of  Weismann,  see  Romanes's  "An  Examination  of  Weismann- 
ism,"  1893. 

4  It  is  of  interest  to  note  that  the  strongest   defenders  of  neo- 
Darwinism  to-day  are  the  English  naturalists.     Americans  mostly 
lean  toward  neo-Lamarckism ;  the  Germans  are  divided. 

5  Plate,   Ludwig,   "Uber  die   Bedeutung  des  Darwin'schen   Selec- 
tionsprinzip  und  Probleme  der  Artbildung,"  2d  ed.,  1903. 

6  Prof.   Weldon,   an    English   Darwinian,    has   recorded    {Nature, 
Sept.  22,  1898)  an  extremely  interesting  and  much  discussed  statis- 
tical and  experimental  study  of  the  presumable  action  of  natural 
selection  working  on   slight  fluctuating  quantitative   variations.     "I 
can  only  attempt  to  discuss,"  says  Prof.  Weldon,  "the  importance 
of  small  variations,  and  the  rate  of  organic  change,  in  the  one  case 
which  I  happen  to  know.    The  particular  case  I  have  myself  studied 
is  the  variation  in  the  fronta.1  breadth  of  Carcinus  mamas  [a  small 
shore-crab]. 


158  DARWINISM   TO-DAY. 

"During  the  last  six  years  my  friend,  Mr.  Herbert  Thompson,  and 

I   have   studied  in   some  detail   the  state  of  this  character  in  the 

Weldon's  ex-      small  shore-crabs    which  swarm  on  the  beach  below 

periments  on        the  laboratory  of  the  Marine  Biological  Association, 

Carcinus.  at  Plymouth. 

"I  will  show  you  that  in  those  crabs  small  changes  in  the  size  of 
the  frontal  breadth  do,  under  certain  circumstances,  affect  the  death- 
rate,  and  that  the  mean  frontal  breadth  among  this  race  of  crabs  is, 
in  fact,  changing  at  a  rate  sufficiently  rapid  for  all  the  require- 
ments of  a  theory  of  evolution. 

"In  Table  IV  [omitted],  you  see  three  determinations  of  the 
mean  frontal  breadth  of  these  crabs,  expressed  in  terms  of  the 
carapace-length,  taken  as  1,000.  You  see  that  the  mean  breadth 
varies  very  rapidly  with  the  length  of  the  crab,  so  that  it  was  neces- 
sary to  determine  it  separately  in  small  groups  of  crabs,  such  that 
the  length  of  no  two  crabs  in  a  group  differed  by  more  than  a 
fifth  of  a  millimetre.  The  first  column  of  the  table  shows  you  the 
mean  frontal  breadth  of  twenty-five  such  groups,  between  10  and  15 
millimetres  long,  collected  in  1893.  These  crabs  were  measured  by 
Mr.  Thompson.  The  second  column  shows  you  the  mean  frontal 
breadth  in  twenty-five  similar  groups  of  crabs,  collected  in  1895,  and 
also  measured  by  Mr.  Thompson.  You  see  that  in  every  case  the 
mean  breadth  in  a  group  of  crabs  collected  in  1895  is  less  than  it 
was  in  crabs  of  the  same  size  collected  in  1893.  The  third  column 
contains  the  result,  so  far  as  it  is  yet  obtained,  of  my  own  measure- 
ment of  crabs  collected  this  year.  It  is  very  incomplete,  because 
the  1895  crabs  were  collected  in  August  and  September,  and  I  was 
anxious  to  compare  them  with  crabs  collected  this  year  at  the  same 
season,  so  that  there  has  not  yet  been  time  to  measure  the  whole 
series.  The  measurements  are  sufficient,  however,  to  show  that 
the  same  kind  of  change  has  taken  place  during  the  last  three 
years  as  that  observed  by  Mr.  Thompson  in  the  interval  between 
1893  and  1895.  Making  every  allowance  for  the  smallness  of  the 
numbers  so  far  measured  this  year,  there  is  no  doubt  whatever  that 
the  mean  frontal  breadth  of  crabs  from  this  piece  of  shore  is 
considerably  less  now  then  it  was  in  1895  among  crabs  of  the 
same  size.* 

"These  results  all  relate  to  male  crabs.     The  change  in  female 

*  I  shall,  of  course,  consider  it  my  duty  to  justify  this  statement 
by  more  extensive  measurement  as  soon  as  possible.  In  the  mean- 
time I  may  say  that  I  have  measured  other  small  groups  of  crabs, 
male  and  female,  from  the  same  place,  at  different  seasons  of  the 
years  1896-98,  and  the  results  agree  with  those  recorded  in  the 
table. 


DARWINISM   DEFENDED.  159, 

crabs  during  this  time  has  been  less  than  the  change  in  male  crabs, 
but  it  is,  so  far  as  my  measurements  at  present  permit  me  to  speak,, 
going  on  in  the  same  direction  as  the  change  in  male  crabs. 

"I  think  there  can  be  no  doubt,  therefore,  that  the  frontal  breadth. 
of  these  crabs  is  diminishing  year  by  year  at  a  rate  which  is  very 
rapid,  compared  with  the  rate  at  which  animal  evolution  is  com- 
monly supposed  to  progress. 

"I  will  ask  your  patience  for  a  little  while  longer,  that  I  may 
tell  you  why  1  feel  confident  that  this  change  is  due  to  a  selective 
destruction,  caused  by  certain  rapidly  changing  conditions  of 
Plymouth  Sound. 

"On  either  side  of  Plymouth  itself  a  considerable  estuary  opens 
into  the  Sound,  and  each  of  these  estuaries  brings  down  water 
from  the  high  granite  moorlands,  where  there  are  rich  deposits  of 
china  clay.  Those  of  you  who  know  Dartmoor  will  remember  that 
in  rainy  weather  a  great  deal  of  china  clay  is  washed  into  the 
brooks  and  rivers,  so  that  the  water  frequently  looks  white  and. 
opaque,  like  milk.  Much  of  this  finely  divided  china  clay  is  carried 
down  to  the  sea;  and  one  effect  of  the  breakwater  has  been  to 
increase  the  quantity  of  this  fine  silt  which  settles  in  the  Sound 
itself,  instead  of  being  swept  out  by  the  scour  of  the  tide  and  the 
waves  of  severe  storms. 

"So  that  the  quantity  of  fine  mud  on  the  shores  and  on  the  bot- 
tom of  the  Sound  is  greater  than  it  used  to  be,  and  is  constantly 
increasing. 

"But  this  is  not  all.  During  the  forty  or  fifty  years  which  have- 
gone  by  since  the  breakwater  was  completed,  the  towns  on  the 
shores  have  largely  increased  their  population ;  the  great  dockyard 
at  Devonport  has  increased  in  size  and  activity;  and  the  ships 
which  visit  the  Sound  are  larger  and  more  numerous  than  they 
were.  Now  the  sewage  and  other  refuse  from  these  great  and 
growing  towns  and  dockyards,  and  from  all  these  ships,  is  thrown 
into  the  Sound;  so  that  while  it  is  more  difficult  than  it  used  to  be 
for  fine  silt  to  be  washed  out  of  the  Sound,  the  quantity  thrown  into 
it  is  much  greater  than  it  was,  and  is  becoming  greater  every  day. 

"It  is  well  known  that  these  changes  in  the  physical  conditions 
of  the  Sound  have  been  accompanied  by  the  disappearance  of  ani- 
mals which  used  to  live  in  it,  but  which  are  now  found  only  outside 
the  area  affected  by  the  breakwater. 

"These  considerations  induced  me  to  try  the  experiment  of  keeping 
crabs  in  water  containing  fine  mud  in  suspension,  in  order  to  see 
whether  a  selective  destruction  occurred  under  these  circumstances 
or  not.  For  this  purpose,  crabs  were  collected  and  placed  in  a  large 
vessel  of  sea-water,  in  which  a  considerable  quantity  of  very  fine.- 


160  DARWINISM   TO-DAY. 

china  clay  was  suspended.  The  clay  was  prevented  from  settling 
by  a  slowly  moving  automatic  agitator ;  and  the  crabs  were  kept 
under  these  conditions  for  various  periods  of  time.  At  the  end 
of  each  experiment  the  dead  were  separated  from  the  living,  and 
both  were  measured. 

"In  every  case  in  which  this  experiment  was  performed  with 
china  clay  as  fine  as  that  brought  down  by  the  rivers,  or  nearly  so, 
the  crabs  which  died  were  on  the  whole  distinctly  broader  than 
the  crabs  which  lived  through  the  experiment,  so  that  a  crab's 
chance  of  survival  could  be  measured  by  its  frontal  breadth. 

"When  the  experiment  was  performed  with  coarser  clay  than 
this,  the  death-rate  was  smaller,  and  was  not  selective. 

"I  will  rapidly  show  you  the  results  of  one  or  two  experiments. 
The  diagram  [omitted]  shows  the  distribution  of  frontal  breadths, 
about  the  average  proper  to  their  length,  in  248  male  crabs  treated 
in  one  experiment.  Of  these  crabs,  154  died  during  the  experiment, 
and  94  survived.  The  distribution  of  frontal  breadths  in  the  sur- 
vivors is  shown  by  the  lower  curve  in  the  diagram,  and  you  see 
that  the  mean  of  the  survivors  is  clearly  below  the  mean  of  the 
original  series,  the  mean  of  the  dead  being  above  the  original  mean. 

"Two  other  cases,  which  are  only  examples  of  a  series  in  my 
possession,  show  precisely  the  same  thing. 

"These  experiments  seemed  to  me  to  show  that  very  finely  divided 
china  clay  does  kill  crabs  in  such  a  way  that  those  in  which  the 
frontal  breadth  is  greatest  die  first,  those  in  which  it  is  less  live 
longer.  The  destruction  is  selective,  and  tends  to  lower  the  mean 
frontal  breadth  of  the  crabs  subjected  to  its  action.  It  seemed  to 
me  that  the  finer  the  particles  used  in  the  experiments,  that  is  to 
say,  the  more  nearly  they  approached  the  fineness  of  the  actual  silt 
on  the  beach,  the  more  selective  their  action  was. 

"I,  therefore,  went  down  to  the  beach,  where  the  crabs  live,  and 
looked  at  the  silt  there.  This  beach  is  made  of  moderately  small 
pieces  of  mountain  limestone,  which  are  angular  and  little  worn 
by  water.  The  pieces  of  limestone  are  covered  at  low  tide  with 
a  thin  layer  of  very  fine  mud,  which  is  much  finer  than  the  china 
clay  I  had  used  in  my  experiments,  and  remains  suspended  in 
still  water  for  some  time.  Under  these  stones  the  crabs  live,  and 
the  least  disturbance  of  these  stones  raises  a  cloud  of  very  fine 
mud  in  the  pools  of  water  under  them.  By  washing  the  stones  of 
the  beach  in  a  bucket  of  sea-water,  I  collected  a  quantity  of  this 
very  fine  mud,  and  used  it  in  a  fresh  series  of  experiments,  precisely 
as  I  had  before  used  china  clay,  and  I  obtained  the  same  result. 
The  mean  frontal  breadth  of  the  survivors  was  always  smaller 
than  the  mean  frontal  breadth  of  the  dead. 


DARWINISM    DEFENDED.  161 

"I  think,  therefore,  that  Mr.  Thompson's  work,  and  my  own, 
have  demonstrated  two  facts  about  these  crabs;  the  first  is  that 
their  mean  frontal  breadth  is  diminishing  year  by  year  at  a  measur- 
able rate,  which  is  more  rapid  in  males  than  in  females;  the  second 
is  that  this  diminution  in  the  frontal  breadth  occurs  in  the  presence 
of  a  material,  namely,  fine  mud,  which  is  increasing  in  amount, 
and  which  can  be  shown  experimentally  to  destroy  broad-fronted 
crabs  at  a  greater  rate  than  crabs  with  narrower  frontal  margins. 

"I  see  no  shadow  of  reason  for  refusing  to  believe  that  the  action 
of  mud  upon  the  beach  is  the  same  as  that  in  an  experimental 
aquarium;  and  if  we  believe  this,  I  see  no  escape  from  the  con- 
clusion that  we  have  here  a  case  of  Natural  Selection  acting  with 
great  rapidity,  because  of  the  rapidity  with  which  the  conditions 
of  life  are  changing." 

These  observations  and  conclusions  of  Professor  Weldon  have 
been  the  subject  of  much  discussion.  The  adverse  criticism  has,  on 
the  whole,  seemed  to  be  successful  in  discrediting  the  case  as  an 
example  of  any  such  clear-cut  action  of  natural  selection,  as  Weldon 
seems  to  hold  it  to  be.  J.  T.  Cunningham  (Natural  Science,  Vol. 
XIV,  pp.  38-45,  1899)  concludes,  after  a  critical  analysis  of  the 
work,  that  "Weldon's  observations  may  be  completely  explained  by 
variations  in  the  amount  or  rate  of  growth.  The  difference  in 
different  years  would  be  at  once  explained  if  the  amount  of  change 
in  frontal  breadth  was  constant  for  each  moult,  while  the  amount 
of  growth  was  variable.  The  fact  is,  that  in  1893  crabs  of  a  given 
frontal  breadth  were  larger  than  in  1895  and  1898;  and  I  have 
shown  that  the  summer  of  1893  was  exceptionally  fine  and  warm. 
Either  the  warmth  alone,  or  warmth  and  food  together,  very  prob- 
ably made  the  crabs  grow  more  in  that  year  for  the  same  number 
of  moults.  On  this  view  the  broad-fronted  crabs  died  in  the  expe- 
riments with  clay  and  mud  because  they  were  younger  and  weaker. 
In  the  same  way  the  crabs  that  moulted  in  the  bottles  possibly 
grew  more  than  those  in  the  sea,  because  they  were  kept  in  warmer 
water  and  supplied  with  more  food.  Therefore  they  were,  after 
the  moult,  larger  than  those  in  the  sea  of  the  same  relative  frontal 
"breadth. 

"The  change  described  is  not,  if  terms  are  used  correctly,  a  change 
in  the  character  of  the  species,  but  merely  a  change  in  the  rate  of 
development.  The  variations  investigated  are  not  individual  differ- 
ences, since  each  individual  in  the  course  of  its  growth  passes 
through  each  one  of  the  variations  in  its  own  person.  It  has  not 
been  shown  that  the  change  has  gone  on  continuously  for  five 
years,  or  that  it  has  taken  place  only  in  waters  where  there  is  much 
mud.  If  tadpoles  of  the  same  size  were  found  to  have  shorter  tails 


162  DARWINISM   TO-DAY. 

in  one  year  than  in  another,  few  biologists  would  draw  the  con- 
clusion that  the  result  was  due  to  the  selective  destruction  of  those 
with  the  longest  tails.  The  more  probable  explanation  would  be 
that  those  with  the  shorter  tails  were  in  a  more  advanced  stage 
of  their  metamorphosis." 

7  Plate,  L.,  "Uber  die  Bedeutung,"  etc.,  pp.  31-32,  1903. 

8  Tayler,  J.  L.,  "The  Scope  of  Natural  Selection,"  Nat.  Science, 
Vol.  XV,  pp.  114-129,  1899. 

9  Morgan,  C.  Lloyd,  "Factors  in  the  Evolution  of  the  Mammalia," 
Nat.  Science,  pp.  97-101,  1892. 

10  Plate,  L.,  "Uber  die  Bedeutung,"  etc.,  pp.  159-160,  1903. 

11  Tayler,  J.  L.,  "The  Scope  of  Natural  Selection,"  Nat.  Science, 
Vol.  XV,  pp.  114-129,  1899.     I  quote  as  follows:  "In  the  development 

Tayler's  ex-  °*  ^e  individual  we  see  a  disappearance  of  structures, 
planation  of  de-  which  appear  to  become,  with  advancing  development, 
generation  by  useless,  almost  parallel  to  the  gradual  disappearance  of 
natural  selection,  ru(jiments,  etc.,  in  the  history  of  the  species  evolution. 
And  a  common  explanation  for  both  of  these  series  of  phenomena 
can,  I  believe,  be  satisfactorily  found  in  the  known  facts  of  nutrition. 
Growth  of  any  tissue  would  seem  to  depend  on  three  conditions, 
a  stimulus  of  the  part  adequate  to  promote  functional  activity, 
a  proper  food  supply,  and  efficient  removal  of  products  produced 
by  that  particular  tissue's  activity.  There  is  abundant  evidence 
to  prove  that  a  tissue  tends  to  degenerate  if  its  own  excretory 
products  are  not  removed;  the  evil  effects  produced  by  fatigue 
products  in  muscle  and  other  tissues  on  the  activity  of  the  tissue 
itself,  prove  that  this  factor  must  be  of  great  importance  where- 
ever  it  is  found  to  occur.  Just  as  the  growth  and  development  of 
bacteria  are  interfered  with,  and  finally  altogether  checked  by  the 
accumulation  of  products  of  their  own  activity,  so  a  tissue  in  the 
higher  organisms  has  its  activity  impaired  and  its  power  lessened 
when  for  some  reason  diminished  elimination  of  its  own  metabolic 
products  occurs.  Now  both  in  the  development  of  the  individual 
and  the  race  we  see  an  alteration  of  structure,  a  gradual  transition 
from  the  less  to  the  more  specialised,  and  in  this  gradual  transition 
there  must  be,  as  I  endeavoured  to  prove  in  my  answer  to  the  last 
objection,  an  alteration  in  the  line  of  functional  activity  of  the 
parts,  and  that,  owing  to  this  fact,  a  tissue  that  was  necessary  in 
the  earlier  stages  became  less  and  less  so  as  specialisation  advanced, 
the  whole  tendency  of  the  specialising  organism  being  continually 
and  increasingly  against  the  earlier,  less  specialised,  stages.  It  will 
thus  happen  that  every  structure  which  is  becoming  useless,  owing  to 
its  deficient  specialisation,  whether  in  the  history  of  the  race  or  the 
individual,  will  have  two  adverse  sets  of  conditions  to  contend 


DARWINISM   DEFENDED.  163 

with — one,  defective  elimination  of  its  own  tissue  products,  owing 
to  its  becoming  increasingly  removed  from  the  growing  organismal 
specialisation  of  food  products,  while  secondly,  for  this  same  reason, 
its  own  food  supply  will  become  less  and  less  suitable.  This  theory 
would  apply  equally  to  germinal  and  somatic  development  and 
atrophy  of  structure;  there  would  thus,  through  the  alteration  of 
functional  activity  of  the  whole  organism,  be  brought  about  elimina- 
tion of  all  structures  not  in  the  line  of  evolution;  and,  therefore, 
organismal  selection  alone,  if  this  theory  is  sound,  would  be  able 
to  explain  the  complete  disappearance  of  rudiments,  the  various 
forms  of  development  and  atrophy,  without  calling  to  its  aid  climatic 
inheritance,  panmixia,  and  germinal  or  any  other  form  of  particular 
selection." 

12  See  the  account  of  the  observations  of  Kellogg  and  Bell  in  the 
appendix  of  chap.  iv. 

18  Morgan,  C.  Lloyd,  "Animal  Behaviour,"  p.  269. 

14  De  Vries,  H.,  "Die  Mutationstheorie,"  2.  vols.,  1901,  1903. 

15  Plate,  in  a  later  briefer  treatment  ("Darwinismus  kontra  Muta- 
tionstheorie," Archiv  f.  Rassen-  und  Gesellschaft-Biologie,  Vol.  Ill, 

Plate's  expla-  pp.  183-200,  1906)  of  some  of  the  offered  objections  to 
nation  of  charac-  natural  selection  refers  to  this  matter  from  a  slightly 
ter  fixity  in  do-  different  angle.  "So  sehr  der  Ziichter  danach  streben 
mestic  animals,  musgj  erbiich  konstante  Formen  zu  erhalten,  um  der 
Muhe  der  bestandigen  Auslese  enthoben  zu  sein,  so  wenig  spielt  dieser 
Punkt  in  der  freien  Natur  eine  Rolle.  Hier  fmdet  eine  nie  nachlas- 
sende  Zuchtwahl  statt,  wodurch  der  betreffende  Charakter  auf  einer 
gewissen  Hohe  erhalten  und  vor  Riickschlag  bewahrt  wird.  Welcher 
Grad  von  Konstanz  nun  auf  dresem  Wege  im  Laufe  von  Tau- 
senden  von  Generationen  erzielt  werden  kann,  ist  eine  zurzeit 
noch  ungeloste  Frage,  die  ihrer  Natur  nach  wohl  kaum  mit  Sicher- 
heit  beantwortet  werden  kann.  Jedoch  lehrt  die  Tier-  und  Pflanzen- 
zucht,  dass  der  Riickschlag  nach  dem  Aufhoren  der  Selektion 
um  so  spater  und  um  so  seltener  eintritt,  je  langer  und  je  intensiver 
der  Ziichtungsprozess  vorher  betrieben  worden  ist.  Daraus  ist  zu 
schliessen,  dass  die  langandauernde  Zuchtwahl,  welche  die  Natur 
ausiibt,  jenen  relativ  hohen  Grad  von  Erblichkeit  zu  erzeugen 
vermag,  welcher  den  Spezies-Charakteren  im  allgemeinen  zukommt, 
denn  vollig  konstant  sind  diese  bekanntlich  auch  nicht." 

16  Tayler,  J.  L.,  "The  Scope  of  Natural  Selection,"  Nat.  Science 
Vol.  XV,  p.  119  ff.,  1899. 


CHAPTER  VII. 

DARWINISM  DEFENDED  (CONTINUED)  :  PLATE'S 
CONCILIATORY  DEFENCE. 

THE  foregoing  consideration  of  the  answers  of  the  Dar- 
winians to  the  objections  urged  against  the  effectiveness  of 
the  selection  theory  as  an  explanation  of  evolution  makes 
no  pretence  of  having  included,  or  even  referred  to,  all 
the  arguments  offered  by  the  defenders,  and  it  is  only  fair 
to  note  that  by  no  means  all  Darwinians  and  neo-Darwin- 
ians  agree  to  making  the  concessions  listed  in  the  early 
part  of  the  chapter.  Some  refuse  a  certain  one  or 
two  of  these  concessions,  some  another  or  others,  some 
indeed  will  make  no  admissions  at  all.  With  these  last  we 
are  past  arguing.  The  discussion  assumes  too  much  an  "it 
is,  it  isn't"  character  to  be  particularly  illuminating  or  pro- 
gressive. But  because  of  those  who  concede  in  considerable 
measure,  and  deny  in  some  measure,  the  validity  of  those 
chief  objections  to  the  species-forming  capacity  of  natural 
selection,  the  general  character  of  the  ground  on  which 
this  last  stand  for  the  old  flag  is  being  made  should  at  least 
be  indicated. 

This  half-surrendered  but  still  not  quite  deserted  position 

is  perhaps  most  clearly  to  be  seen  through  the  smoke  of 

Plate's  con-      battle  by  fixing  one's  eyes  on  the  representative 

oVectionstothe  fi&ure  of  Ludwi§"  Plate>  a  strong  Darwinian, 
selection,  but  one  not  blinded  by  prejudice  or  with  ears 

wilfully  closed  to  the  calls  of  reason.  In  his  recent  elaborate 
discussion  l  of  Darwinism,  so  often  already  referred  to  and 
quoted  from  in  these  present  chapters,  he  groups  under  the 
head  of  wesentliche  Einwande  (important  objections)  the 

164 


DARWINISM   DEFENDED.  165 

attacks  on  the  species-forming  capacity  of  natural  selection, 
which  are  based  on  (i)  the  slightness  and  inutility  of  the 
fluctuating  Darwinian  variations,  and  (2)  the  improbability 
of  the  right  variations  appearing  at  the  right  time  to  make 
possible  the  development  of  specialisations  of  qualitative 
and  coadaptive  character.  In  a  discussion  of  some  length 
(pp.  32-77),  mostly  quite  fair  and  unprejudiced,  he  brings 
out  the  best  and  strongest  arguments  that  the  faithful  Dar- 
winians have  to  offer  to  reduce  the  force  of  at  least,  if  not  to 
answer  satisfactorily,  even  for  themselves,  the  most  effective 
attacks  on  the  capacity  of  selection.  In  very  condensed  form 
I  present  in  the  following  paragraphs  the  essential  points 
in  these  defensive  arguments. 

In  regard  to  the  first  objection,  namely,  that  the  very 

slight  or  small  differences  in  organs  and  functions  which 

result  from  the  fluctuating  or  Darwinian  varia- 

The  objection        .  ,  „    . 

to  the  slightness  tions    cannot   be    sufficiently   advantageous    or 

of  Darwinian  disadvantageous  enough  to  afford  "handles" 
variations. 

for  natural  selection,  that  is,  cannot  be  of  life- 

and-death-determining  value,  Darwin  devoted,  in  his  "Origin 
of  Species,"  a  whole  chapter  of  discussion  and  argument 
to  show  that  in  many  cases  even  the  slightest  of  differences 
may  conceivably  (it  is  of  course  a  matter  practically  incapa- 
ble of  proof  by  observation  or  experiment)  be  sufficient  to 
turn  the  scale,  in  a  rigorous  competition,  one  way  or  the 
other.  In  many  other  cases  such  differences  could  not,  even 
to  Darwin,  appear  sufficient  to  be  of  a  life-and-death  advan- 
tage or  disadvantage.  But  Darwin  too  often,  Plate  admits, 
confounded  mere  usefulness  2  with  life-and-death-deciding 
usefulness  (or  non-usefulness). 

However,  for  many  cases  Plate  maintains  that  the  slight 
Darwinian  variations  can  serve  as  handles  for  selection, 
particularly  in  periods  of  unusual  rigour  of  competition 
or  fierceness  of  struggle  (either  active  or  passive)  :  ex- 
amples are,  slight  differences  in  the  speed  of  preyed-on 


166  DARWINISM   TO-DAY. 

animals  when  pursued  by  an  enemy,  or  slight  differences 
in  the  length  of  neck  of  the  giraffe  in  time  of  scarcity  of 
foliage,  or  slight  differences  in  the  effectiveness  of  the 
organs  of  sense  at  times  of  approaching  danger,  or  in 
endurance  of  cold,  heat,  hunger,  dryness,  etc.,  or  in 
the  clothing  of  hairs  or  feathers,  the  number  of  capil- 
laries in  the  skin,  or  richness  of  glandular  secretion,  and 
the  like,  in  times  of  special  stress  of  weather.  "Dodel- 
Port 3  has  shown  that  microscopically  fine  hairs  are  capable 
of  keeping  plant-lice  away  from  leaves  or  buds,  and  that 
very  slight  differences  in  the  specific  gravity  of  the  seeds 
of  water-plants  may  determine  whether  these  seeds  sink  to 
the  bottom  and  consequently  germinate  or  not.  For  the  long 
flights  of  migratory  birds  or  for  birds  like  our  house-doves 
which  protect  themselves  from  birds  of  prey  by  swift  flights 
upward  to  great  heights,  every  smallest  amount  of  advan- 
tage in  the  pneumaticity  of  the  bones  will  be  of  worth  and 
finally  of  vital  advantage,  just  as  every  racing  bicyclist 
knows  by  experience  that  for  his  record-breaking  at- 
tempts he  must  have  a  machine  in  which  every  part  is 
made  as  light  as  possible,  for  the  effects  of  weight  are  cumu- 
lative in  course  of  time."  And  Plate  fills  a  couple  of  pages 
with  other  similar  cases.  "Whoever  scrutinises  the  life  of 
nature  and  of  man  with  biologically  trained  eye  sees  over 
and  over  again  the  coming  of  great  effects  from  slight 
causes.  The  average  of  accidents  in  factories  increases  in 
proportion  to  the  age  of  the  workers,  because  muscular 
strength  and  keenness  of  the  sense  organs  decrease  with 
increasing  age.  In  each  age-class  the  difference  is  but 
slight,  but  in  spite  of  that  it  demands  its  sacrifice.  Nageli, 
in  a  paper  concerning  the  abundance  of  tuberculosis,  showed 
that  among  500  dead  human  bodies  examined  97  per  cent, 
showed  traces,  at  least,  of  tuberculosis.  That  is,  practically 
every  adult  human  is  tainted  by  this  disease.  Now  how 
often  must  slight  differences  in  body  structure,  life  habits, 


DARWINISM   DEFENDED.  167 

hygienic  conditions,  yes,  even  in  temperament,  determine 
whether  there  shall  be  healing  or  death?  The  iridescent 
colours  of  many  male  birds,  butterflies,  and  certain  parasitic 
copepods  (Sappharina),  are  certainly  of  a  nature  to  pro- 
duce a  great  effect  on  the  eye,  but  these  colour  effects  are 
not  the  result  of  special  pigments  but  of  microscopically 
minute  structural  conditions.  In  Africa  the  tsetse-fly  4  ex- 
tends over  large  regions,  and  only  those  cattle  with  a  skin  of 
a  certain  thickness,  so  that  the  tiny  proboscis  of  the  fly 
cannot  penetrate  it,  can  live  in  these  regions  immune  from 
the  fatal  attacks  of  the  pest.  Many  poisons  work  in  almost 
infinitely  weak  dilution — a  1-200,000  solution  of  ricin,  for 
example,  is  able  to  kill  mice." 

Plate  presents  a  second  type  of  answer  to  the  objection 

by  calling  on  certain  aids  or  auxiliary  principles  by  whose  in- 

.   ,         fluence  a  difference  at  first  unimportantly  small 

Correlation  J 

may  aid  slight  gradually  comes  to  be  transformed  into  one  of 
variations.  selective  value,  or  may  reach  this  stage  sud- 
denly by  means  of  a  change  in  life  habits.  This  may  come 
about  "through  correlation,5  that  is,  through  that  unknown 
law  of  growth  by  which  an  indifferent  organ  may  be  so 
bound  up  with  or  related  to  a  useful  organ  6  that  it,  the 
indifferent  organ,  is  perfected  along  with  the  useful  organ 
as  this  latter  is  developed  or  specialised  through  selection. 
All  organs  of  an  animal  are  intimately  related  to  and  influ- 
enced by  one  another:  each  is  in  relation  to  the  other  just 
as  to  the  outer  world.  How  close  this  inter-dependence  is, 
is  most  easily  appreciated  by  one  in  his  own  case  when  sick : 
a  constipation  causes  headache,  a  slight  diarrhoea  affects  the 
composition  of  the  urine,  etc.  The  correlation  can  be  so 
intimate  and  important,  as  the  case  of  the  secondary  sexual 
characters  shows,  that  its  origin  and  development  depends 
directly  on  particular  definite  stages  of  the  related  organs." 
In  the  case  of  many  animals  the  appearance  of  various  curi- 
ous and  large  modifications  of  legs,  wings,  skin,  feathers, 


168  DARWINISM   TO-DAY. 

hair,  etc.,  etc.,  depends  on  the  various  stages  of  development 
reached  by  the  reproductive  organs.  Now  these  secondary 
organs  or  modifications  thus  produced  through  the  influence 
of  other  organs  may  be  for  a  while  slight  and  indifferent 
in  character,  but  yet  safely  maintained.  When  they  reach 
a  stage  of  utility  or  of  positive  disadvantage  they  will  then 
be  further  perfected,  or  on  the  other  hand  be  extinguished, 
by  selection. 

The   principle   of   the    change    of    function    (Functions- 

wechsel)  first  elaborated  by  Dohrn,7  is  also  called  on  by 

Dohrn's  rin-    -^ate  to  plav  an  important  part  in  explaining 

ciple  of  change     how  an  organ  of  considerable  specialisation  can 

f  function,         ^  sjlown  to  have  been  devei0pe(i  by  selection, 

although  the  function  it  is  now  performing  seems  to  be  one 
that  could  have  been  useful  only  in  a  perfected  state  and 
hence  could  not  have  made  the  organ  so  constantly  ad- 
vantageous in  all  the  slow  and  gradual  stages  of  its  evolution 
as  to  be  of  selective  value  in  its  beginning  stages.  Dohrn's 
principle  is  stated  as  follows :  "An  organ  can,  in  its  service 
of  a  certain  definite  useful  function,  be  developed  by  natural 
selection  to  a  certain  stage.  Simultaneously  a  second  func- 
tion (Fiinctionserweiterung)  can  have  developed,  due  to 
some  special  peculiarity  or  condition  of  the  position,  struc- 
ture, or  capacity  for  movement,  which  may  have  a  value  in 
another  direction  from  that  of  the  first  function.  Thus 
the  appendages  of  crabs  serve  often  special  functions  in  rela- 
tion to  respiration,  copulation,  and  care  of  the  eggs  or 
young,  while  their  original  locomotory  function  may  still 
be  maintained  or  may  be  more  and  more  surrendered  in 
favour  of  the  new  functions."  Numerous  other  specific  ex- 
amples are  obvious  enough  to  any  student  of  biology.  Now 
the  new  functions  in  many  cases  become  the  more  import- 
ant so  that  there  in  time  results  a  complete  change  of  func- 
tion which  wholly  alters  the  physiological  character  of  the 
organ,  and  in  many  cases  it  is  difficult  to  see  (if  one  does- 


DARWINISM    DEFENDED.  169 

not  know  the  phyletic  history  of  the  organ  and  the 
function)  just  how  selection  could  have  developed  such  an 
organ  by  slow  degrees  from  slight  beginnings.  But  the 
secret  of  the  explanation,  which  is  a  perfectly  consistent 
Darwinian  explanation,  lies  in  the  Functionswechsel  phe- 
nomenon. 

''Indifferent  characters  can  suddenly  become  of  selective 
value  through  change  of  environmental  conditions  or  of 
life-habits.  The  cranial  sutures  are  certainly  of  no  vital 
importance  with  the  reptiles  and  birds,  but  they  can  be  of 
very  great  importance  to  the  viviparous  mammals  as  adapta- 
tions for  passing  the  pelvis  during  birth.  Lacerla  vivipara 
has,  perhaps,  no  advantage  through  its  viviparousness  over 
its  nearly  related  species  in  our  country,  but  in  Scandinavia 
it  has  to  thank  this  peculiarity  alone  for  its  success  in  life,, 
because  the  development  of  its  young  is  rendered  inde- 
pendent of  the  sun  by  it.  The  nectaries  were  probably  at 
first  useless  to  the  flowers;  from  that  moment,  however, 
when  the  insects  learned  to  know  them  as  food  reservoirs 
and  unwittingly  insured  cross-pollination  by  their  visits  to 
them,  they  became  of  the  greatest  importance  and  the  indi- 
rect cause  of  the  origin  of  the  colour  brilliance  of  the 
flowers. 

"There  are  organs  of  universal  character  which  can  be- 
come modified  in  most  widely  differing  directions.  Thus 
the  tail  of  the  mammals,  originally  a  long,  evenly-haired 
organ,  can,  without  going  through  any  very  elaborate 
changes,  be  modified  into  a  bushy  steering-rudder  of  special 
use  in  climbing  from  branch  to  branch ;  or  by  the  outgrowth 
of  a  terminal  tuft  be  changed  into  a  flying  fan ;  or  by  the  par- 
tial loss  of  the  hair  become  a  grasping  organ,  or  a  balancing 
organ,  or  an  aid  in  leaping,  a  rudder  in  swimming,  or  a  cover 
against  rain  and  cold  (Myrmecophaga  jubata).  The  append- 
ages of  crabs,  the  cirri  of  the  annelids,  and  the  teeth  of  mam- 
mals are  further  examples  of  a  similar  plasticity  and  capacity 


«7°  DARWINISM   TO-DAY. 

for  modification  in  the  most  manifold  ways,  in  which  the 
first  stages  are  often  of  immediate  use." 

Following  these  suggestions  as  to  the  aid  that  selection 
may   have   from   various   helping   conditions   to   make   its 
starts,  Plate  discusses  as  further  similarly  help- 
aid  from  in-         ^ul  conditions  or  auxiliary  principles  three  most 
herited  results     important  matters,  namely,  the  effects  of  con- 

of  use,  from  or-  ,  . 

thogenesis  and     tinued  use  on  parts,  the  principle  of  orthogen- 

discontinuous  esjSj  an(j  the  facts  of  sudden  discontinuous 
variation! 

variation.      But   as   these   three   categories   of 

biological  phenomena  and  principles  are  exactly  those, 
among  others,  which  anti-Darwinians  hold  to  be  not  aids 
to  the  selection  theories,  but  to  be  the  basis  if  not  of  actually 
replacing  or  substitutionary  theories,  at  least  of  precisely 
those  objections  to  the  species-forming  capacity  of  the  strict 
Darwinian  factors  which  have  necessitated  some  of  the 
principal  concessions  made  by  the  Darwinists,  it  is  obvious 
that  Plate's  discussion  of  them  is  in  itself  simply  the  actual 
making  of  the  concessions  already  noted  as  having  been 
admitted  by  most  Darwinians.  Each  of  these  categories 
of  phenomena  and  principles  is  of  course  of  much  import- 
ance and  interest,  and  they  will  all  be  found  to  be  fairly  fully 
set  out  in  the  chapters  following  this  one. 

Plate's  answers  to  the  second  important  objection,  namely, 
that  selection  relies  too  much  on  chance  and  is  therefore 

.  improbable  and  inexact,  may  now  be  noted.    He 

Answers  to  . 

the  objection       distinguishes  two  phases  of  this  objection.    The 

repfcnSerf6  first  he  exPresses  as  follows :  "It  is  highly  im- 
selectionon  probable  that  for  the  progressive  development 
or  perfecting  of  an  organ  there  will  always 
appear  just  at  the  needed  time  the  variation  necessary  for 
selection,  that  is,  the  exactly  needed  adaptive  modification." 
The  second  phase  is :  "It  is  highly  improbable  that  in  the 
development  of  a  complicated  organ,  or  body-part,  or  in 
the  perfecting  of  a  changing  adaptation  the  numerous  indis- 


DARWINISM   DEFENDED.  171 

pensable  modifications  will  appear  in  such  a  series  that  a 
harmonious  correlation  of  the  single  variations  will  be 
possible." 

Referring  especially  to  the  first  phase  of  the  general  ob- 
jection he  says  : 

"Thus  this  doubting  query  is,  why  do  there  always  appear 
just  the  right  variations  at  the  right  time?  Or,  somewhat 
differently  expressed,  in  the  words  of  Cope,8  'since  the 
number  of  variations  possible  to  the  organism  is  very  great, 
the  probability  of  the  admirably  adaptive  structures  which 
characterise  the  latter  having  arisen  by  chance  is  extremely 
small.' 

"Whoever  expresses  such  doubts  unwittingly  hitches  the 
wagon  before  the  horse.  Selection  directs  itself  according 
to  the  variation,  not  variation  according  to 
selection.  If  the  variability  is  .large,  selection 


not  variation  has  a  large  choice;  if  the  variability  is  small, 
then  there  are  but  few  lines  of  evolution  open. 
Experience  teaches  that  in  general,  the  variability  of  organ- 
isms is  very  large,  that  it  occurs  both  quantitatively  and 
qualitatively  in  such  pronounced  manner  in  all  individuals 
of  a  species  that  it  can  be  readily  recognised  without  re- 
course to  complex  methods  of  investigation,  and  that  no 
characteristic  (size,  form,  colour,  numerical  relation,  consti- 
tutional vigour,  instinct,  life-habit)  is  free  from  it  in  any 
life  stage  from  egg  to  last  drawing  of  the  breath.  It  is 
precisely  to  this  variability  expressing  itself  in  the  most 
manifold  ways  and  combinations  that  is  to  be  ascribed  the 
condition  that  any  individual  as  such  is,  usually,  readily 
to  be  distinguished  from  other  individuals  of  the  same 
species.  It  results  from  this  that  the  individual  variation  is 
indeterminate  and  undirected,  or  better  expressed,  universal 
and  all  sided,  and  that  at  any  given  moment  the  exactly 
needed  modification  will  always  appear  in  a  number  of  indi- 
viduals of  any  species  rich  in  individuals,  provided  that 


172  DARWINISM    TO-DAY. 

the  needed  variation  can  be  produced  through  a  slight  ad- 
vance or  progressive  change.  Naturally  it  is  not  sufficient 
if  the  variation  appears  in  only  a  few  isolated  individuals, 
but  it  is  necessary,  for  the  modification  of  the  species,  that 
this  variation  occur  in  so  many  individuals  that  it  will  not 
be  extinguished  through  interbreeding  but  on  the  contrary 
will  be  perpetuated.  In  other  words  selection  works,  except 

Selection  works  m  scattere<^  cases  where  single  or  rare  varia- 
with  plural  vari-  tions  are  specially  favoured  by  accidental  iso- 
lation, not  with  single  but  with  plural  variations 
or  varieties.  Through  this  the  host  of  variations  is  im- 
mensely reduced  as  far  as  they  come  into  consideration  as 
handles  for  selection,  and  of  course  only  in  this  sense  is 
there  any  reason  at  all  for  the  query  as  to  whether  we  can 
assume  that  the  right  variation  will  always  be  present  at  the 
right  time.  The  answer  can  only  be,  certainly  not  always : 
many  promising  beginnings  must  always  be  checked  in  the 
germ  or  at  half-way,  but  in  infinitely  many  cases  the  needed 
plural  variation  will  appear,  because  the  same  external 
factors  change  a  whole  group  of  animals  simultaneously 
so  that  progress  is  possible.  But,  it  goes  without  saying, 
only  a  slow  advance  is  conceivable  on  this  basis. 

"One  must  not,  for  the  rest,  forget  that  the  same  condi- 
tion of  selective  worth  may  be  reached  simultaneously 

through  combinations  of  different  peculiarities, 
Same  selective          ,    A ,         A ,  ~ 

value  may  be       anc*  that  the  same  effect  may  be  attained  by 

attained  in  dif-     various  means,  both  of  which  facts  render  it 

ferent  ways. 

importantly  easier  to  get  this  selective  worth. 
When  pursued  by  an  enemy  one  individual  of  the  harassed 
species  may  save  itself  by  a  quick  leap,  a  second  through 
sharp  ears,  a  third  by  sharp  eyes.  Wallace  rightly  explains 
that  the  necessity  for  a  giraffe  in  times  of  famine  is  only  to 
reach  as  high  as  possible  in  the  trees,  and  that  different 
means  may  avail  for  this,  as  a  longer  neck,  long  legs,  or  a 
long  tongue,  all  of  which  may  eventually  come  to  be  correl- 


DARWINISM   DEFENDED.  i?3 

atively  increased.  The  individuals  which  survive  by  these 
aids  may  then  later,  through  inter-crossing,  exchange  their 
advantages  and  so  lead  to  the  production  of  a  mean  type 
that  shows  a  slight  advance  over  earlier  conditions  in  all 
three  organs.  Mammals  can  protect  themselves  from  flies 
in  various  ways,  either  by  a  thick  fur  (bears),  by  reflexive 
twitchings  of  the  skin  muscles  (horse),  by  tails  with  tufted 
ends  (many  hoofed  animals),  by  a  long  neck  which  can  bend 
sideways  so  that  the  animal  can  reach  any  part  of  its  body 
as  far  as  the  hips  (guanaco,  stag)  or  finally  by  eyelids  and 
long  movable  ears,  which  restrain  the  flies  from  the  easily 
injured  eyes.  These  means  of  protection  from  insects  play 
an  important  role  in  determining  the  habitus  of  many  mam- 
mals, and  permit  the  conclusion  that  selection  has  been 
instrumental  in  producing  this  habitus.  Here,  also,  it  is 
possible  for  several  of  these  means  to  be  possessed  at  once 
by  the  same  animal,  as  in  the  case  of  the  guanaco  with  its 
long  hair  and  elongate  neck.  It  is  absolutely  necessary  for 
molluscs  that  live  between  tide-lines  to  have  some  means  of 
resisting  the  force  of  the  surf.  Many  species  possess  this 
means  in  their  small  size  which  allows  them  to  crawl  into 
crevices  and  cracks  in  the  rocks,  but  most  of  them  have 
developed  a  strong  pedal  sucker  and  a  low  roof-like  uncoiled 
shell  which  presses  close  to  the  rock  surface  and  over  which 
the  water  flows  without  exerting  any  strong  lateral  pres- 
sure. This  is  the  case,  for  example,  with  Patella,  Fissurella, 
Chiton,  Concholepas,  Siphonaria,  Gadinia,  Calyptra,  and 
others.  All  three  of  these  means  of  safety  can  come  into 
play  simultaneously  in  selection,  but  it  suffices  when  any 
given  individual  possesses  any  one  of  these  means  in  suffi- 
cient degree  of  development. 

"I  shall  note  here  several  other  examples  which  show 
how  related  species  reach  the  same  advantage  in  the  strug- 
gle through  different  means,  for  we  can  assume  from  these 
facts  that  also  the  individuals  of  the  same  species  often 


174  DARWINISM   TO-DAY. 

escape  the  same  dangers  in  the  struggle  for  existence  by 
means  of  different  means.  And  by  this  the  probability  is 
made  greater  that  the  'needed  variation'  appears  at  the 
right  time.  The  differing  characteristics  of  this  sort  will 
later  lead,  through  crossing,  to  the  formation  of  a  mixed 
type,  or,  if  the  competition  grows  ever  sharper  with  the 
course  of  time,  they  will  produce  a  separation  of  the  species 
into  varieties  (eventually  species)  with  differing  habits  of 
life,  or  finally  they  may  meet  in  direct  competition  or  strug- 
gle with  one  another.  The  good  flyers  among  the  birds  all 
have  long  wings,  but  in  some  it  is  the  fore  arm  which  is 
specially  lengthened  (cuckoo,  goat-sucker,  pigeon),  in  others 
the  hand  (terns,  humming-birds,  eave  swallows),  and  in 
still  others  the  upper  arm  (swan). — While  Tapirus  ameri- 
canus,  like  most  mammals,  drives  the  flies  away  from  its 
eyes  by  throwing  down  the  eyelids,  Tapirus  indicus  accom- 
plishes the  same  thing  by  a  strong  rotation  of  the  bulb  of 
the  eye.  Elephas  africanus  seizes  very  small  objects  with 
its  proboscis-fingers,  while  the  Indian  elephant  lays  the  front 
end  of  the  trunk  laterally  on  the  ground,  grasps  the  object 
between  the  skin-folds,  lifts  it  up  high  in  this  way,  and 
only  then  allows  it  to  fall  into  the  tip  of  the  proboscis. — 
Poulton  has  shown  by  several  examples  that  in  cases  of 
mimicry  the  same  effects  may  be  got  in  very  different  ways. 
The  glass-like  transparency  of  the  wings,  for  example,  is  got 
in  the  Heliconid  genus  Menthona  by  a  considerable  dimi- 
nution in  size  of  the  scales,  in  the  Danaid  Ituna  iliona  through 
the  absence  of  most  of  the  scales,  in  Castnia  linus  var.  heli- 
conoidcs,  through  the  absence  of  pigment  in  the  scales,  which 
are  as  large  and  numerous  as  usual,  in  the  Pierid  Dismor- 
phia  crise  through  the  smallness  of  the  scales,  and  finally  in 
the  night  moth  Hyelosia  heliconoides  by  the  absence  of  pig- 
ment and  lessened  number  of  the  scales." 

Plate  next  offers  a  detailed  explanation  on  strict  Darwin- 
ian grounds   of  how   such   an   extraordinary  condition  of 


DARWINISM   DEFENDED.  175 

mimicry  can  be  brought  about  as  the  famous  case  of  Kal- 
lima,  the  butterfly  that  simulates  in  colour,  shape,  and  inti- 
mate details  of  pattern  such  as  veins,  flecks, 

fun£us  sP°ts>  etc->  a  dead  leaf  with  such  ndelit7 
as  to  make  it  the  wonder  of  every  one  who  sees 

it  and  the  classic  example  of  the  possibilities  of  such  protect- 
ive resemblance.  And  he  shows  well  that  whatever  diffi- 
culties selection  may  have  in  its  necessary  dependence  on 
the  chance  occurrence  of  the  proper  numerous  and  neces- 
sarily simultaneously  appearing  variations  to  explain  the 
gradual  development  of  such  a  specialisation,  the  only  other 
explanations  so  far  offered  are  even  more  ludicrously  de- 
pendent on  "luck."  Piepers,9  the  most  active  and  polem- 
ically vigorous  of  all  special  opponents  of  the  Darwinian 
explanation  of  protective  resemblance  and  mimicry,  says  r 
"Chance  alone  can  bring  about  such  a  correlation."  As 
Plate  well  says,  "It  is  not  without  its  comic  aspect  that  a 
violent  antagonist  of  the  selection  theory  should  be  found 
clinging  to  the  same  safety-anchor  'chance,'  that  usually 
is  the  constant  reproach  of  the  Darwinian.  ...  It  would  not 
be  difficult,"  continues  Plate,  "to  refer  to  still  other  examples 
to  show  that  a  needed  selective  value  can  often  be  attained 
at  the  same  time  by  the  individuals  of  a  species  through 
various  means,  by  which  the  probability  that  this  type  of 
adaptations  can  arise  is  correspondingly  increased.  But 
one  point  should  never  be  forgotten  and  that  is  it  is  always 
first  the  variability,  and  second  the  selection.  If  no  varia- 
tions appear  there  can  be  no  progress,  and  if  the  struggle 
for  existence  were  too  severe  the  [non-varying]  species 
would  die  out.  Strictly  speaking,  the  question,  how  is  it 
possible  that  the  right  variations  can  be  relied  on  to  ap- 
pear at  the  right  time?  is  really  inverted  and  therefore 
incapable  of  receiving  a  correct  answer.  One  can  only 
say:  If  a  complex  adaptation  has  arisen  through  selec- 
tion, then  it  is  certain  that  the  necessary  modifications 


*76  DARWINISM   TO-DAY. 

needed  for  success  in  the  struggle  for  existence  were  not 
wanting." 

We  come  now  to  the  second  phase  of  the  general  objec- 
tion, as  analysed  by  Plate;  viz.,  the  assumed  improbability 

that  during  the  course  of  the  development 
nmT[t0tb6  (ev°luti°n)  °f  a  complicated  organ  or  whole 
ability  of  the  body-part,  or  during  the  perfecting  of  a  chan- 
ance  of  variaT"  &*n£  adaptation,  the  numerous  necessary  varia- 
tions needed  in  tions  will  occur  in  such  a  successive  series  as 
.structure™  to  make  possible  an  harmonious  correlation  of 

the  various  single  variations.  Plate  writes  as 
follows :  "This  objection  has  been,  as  is  the  case  with  the 
objection  just  discussed,  raised  by  many  students  of  evolu- 
tion as  Spencer,  Wigand,  Nageli,  and  is  in  principle  not 
different  from  the  previous  objection,  but  only  presents  an 
elaboration  of  it.  It  concerns,  first,  the  numerous  single 
variations  which  are  necessary  if  a  single  complex  organ  (as 
an  eye)  or  a  whole  body- part  with  its  various  organs  and 
tissues  (for  example,  the  neck  of  the  giraffe,  the  fore  body 
of  the  elk)  of  a  single  individual  is  to  be  raised  to  a  higher 
stage  of  adaptiveness ;  and,  second,  the  perfecting  of  inter- 
dependent adaptations  in  different  individuals.  As  example 
of  the  latter  category  I  may  mention  the  corolla  of  flowers 
and  the  proboscis  of  insects  which  cross-pollinate  these 
flowers,  the  male  and  female  copulating  organs  of  many 
animals,  as  those  of  the  Papilionidae,  the  adaptations  of 
myrmecophilous  and  termitophilous  animals  in  relation  to 
their  hosts,  also  those  of  symbiotic  (parasitic  or  mutualistic) 
species  relative  to  their  companions,  and,  in  cases  of  mimicry, 
of  the  mimicking  species  relative  to  the  protected  species. 
When  one  of  the  species,  party  to  such  a  mutual  adaptation, 
changes,  the  other  as  a  rule  must  also.  There  arises  from 
this  the  query :  how,  in  such  cases,  is  there  possible  the  neces- 
sary coadaptation  (coordination),  that  is,  the  harmonious 
•change  of  the  parts  which  produce  the  interdependent  physi- 


DARWINISM   DEFENDED.  17? 

ological  or  biological  phenomena,  whether  these  exist  in  a 
single  individual  or  in  two?  How  does  it  come  that  when 
the  antlers  of  the  giant  stag  become  larger  and  larger,  the 
skull  bones  become  thicker  and  the  neck  tendons  and  the 
fore  legs  stronger  (Spencer)  ?  With  the  gradual  lengthen- 
ing of  the  giraffe's  neck  the  skeletal  system  and  with  it 
numerous  other  closely-related  internal  organs  have  to  be- 
come larger  simultaneously.  Hundreds  of  small  modifica- 
tions are  necessary.  How  does  it  happen  that  all  come  off 
exactly  as  is  necessary?  When  the  flowers'  cups  for  any 
reason  become  deeper  the  insects  must  develop  longer 
proboscides  in  order  to  reach  the  nectaries  in  the  bottom  of 
the  cup.  Simultaneously  the  sucking  apparatus  of  the 
oesophagus  must  change.  How  does  it  happen  that  these 
modifications  in  two  different  organisms,  in  an  animal  and  a 
plant,  occur  part  passuf 

"In  order  to  satisfy  these  questions  of  doubt  Darwin  and 
Wallace  have  referred  to  the  domesticated  animals  as  the 
best  proofs  that  such  coadaptations  are  possible.  A  grey- 
hound, a  bulldog,  a  dachshund,  a  tumbler  pigeon,  a  race- 
horse, have  had  to  pass  through  a  long  series  of  numerous 
changes  in  the  most  various  organs,  in  order  to  reach  their 
present  form,  and  yet  all  these  variations  have  appeared 
one  after  the  other  in  such  a  way  as  never  to  endanger  the 
vital  vigour,  for  man  would  never  have  chosen  weakly  ani- 
mals for  breeding  purposes.  In  artificial  selection,  there- 
fore, coadaptations  are  possible  in  almost  infinite  variety, 
and  it  can  fairly  be  asked  if  such  favourable  conditions  are 
not  also  possible  in  nature.  This  query  must,  a  priori,  be 
answered  in  the  affirmative,  for  man  is  not  able  either  to 
make  more  easy  or  to  hasten  the  appearance  of  coadapta- 
tions :  he  can  only  hold  on  to  those  which  once  appear,  and 
this  can  also  be  done  by  the  struggle  for  existence  in  those 
cases  in  which  the  coadaptive  variations  are  of  vital  import- 
ance. The  real  difference  lies,  therefore,  in  the  fact  that 


178  DARWINISM   TO-DAY. 

man  can  make  a  beginning  with  ever  so  slight  an  advance  ; 
nature  only  with  such  simultaneous  changes  as  are  of  suffi- 
cient grade  or  degree  to  be  of  selective  value.  And  so  far 
in  this  discussion  nothing  has  been  offered  to  show  how  this 
condition  is  to  be  reached." 

To  attempt  to  get  at  an  explanation  of  the  actual  means 
by  which  this  necessary  condition  is  attained,  Plate  believes  it 
Plate's  belief  necessarv  tnat  one  should  make  clear  just  what 
in  the  possibility  standpoint  he  takes  on  the  vexed  problem  of 
tance  of  acquired  tne  inheritance  of  acquired  characters.  With- 
characters,  Ollt  going  into  Plate's  long  discussion  of  this  old 
subject,  it  is  sufficient  to  say  that  he  reaches  the  conclusion 
that  the  inheritance  of  acquired  characters  is  not  proved 
not  to  be  possible,  and  hence  that  it  may  occur.  And,  for 
himself,  he  expresses  the  belief  that  acquired  somatic  char- 
acters can  be  and  are  inherited.  From  this  point  of  view,  he, 
consistently  with  Darwin's  own  position,  finds  an  answer  to 
the  objection  touching  the  necessity  of  a  repetitive  cumulat- 
ing appearance  of  certain  definite  kinds  of  variation  for  the 
basis  of  the  development  of  coadaptation,  by  invoking  the 
Lamarckian  factor  of  the  inheritance  of  the  effects  of  use 
and  functional  stimuli.  Which  refuge  is  of  course  not  open 
to  the  modern  strict  selectionists,  the  neo-Darwinians. 

Now,  as  may  be  imagined,  when  the  Darwinians  them- 
selves are  of  various  minds  about  the  value  of  the  answers 
to  this  objection,  when  these  answers  are  based  on  a  strict 
selection  basis,  they  are  not  very  convincing  to  anti-Darwin- 
ians. In  general  they  rest  on  various  observed  facts  and 
deduced  assumptions  which  may  be  roughly  classified  into 
several  groups.  First,  the  facts  of  simultaneous  correlative 
variation,  or  the  fact  that  organs  or  parts  which  function 
together,  very  often  vary  in  the  same  general  direction.  For 
example,  if  two  leg  or  arm  bones  become  longer  the  muscles 
attaching  to  these  bones  also  become  longer  (since  the 
attachments  are  not  changed).  The  supplying  blood-vessels; 


DARWINISM   DEFENDED.  179 

and  nerves  also  lengthen.  Numerous  observations  by 
breeders  show  that  in  each  organism  there  resides  a  capacity 
of  self-regulation,  up  to  a  certain  degree,  which  produces  a 
harmonious  growth  and  variation  of  inter-dependent  parts. 
If  a  plant  is  removed  to  richly  fertilised  soil  it  will  grow  to 
great  size,  in  the  course  of  which  growth  all  parts  are  pro- 
portionally changed  so  that  the  general  habitus  of  the  plant 
remains  the  same.  If  one  allows  insect  larvae  to  live  on  very 
short  food  rations,  the  adult  insects  will  be  unusually  small 
but  with  all  the  organs  of  their  usual  relation  to  each  other 
as  to  proportional  size.  Thus  it  seems  that  the  single  organs 
are  definitely  correlated  with  one  another  so  that  in  their 
growth  they  maintain  their  relative  characteristics.  "I 
have,"  says  Plate,  "called  this  form  of  organic  Zweckmassig- 
keit  the  unity  of  organisation."  If  this  quality  or  capacity 
is  lacking  in  an  individual  then  it  develops  into  a  cripple,  a 
monster,  and  is  killed  out  by  selection.  Therefore,  if  the 
neck  of  the  giraffe  varies  so  as  to  be  longer,  one  may  fairly 
assume  that,  in  the  case  of  many  individuals,  at  least,  all 
parts  of  the  neck  will  share  in  this  variation,  although  there 
will  naturally  be  slight  individual  varyings  inside  of  this 
general  variation.  And  if  the  antlers  of  the  stag  vary 
towards  a  larger  size  there  will  simultaneously  appear  the 
necessary  increase  in  calcareous  materials  for  all  parts  of 
the  skull,  so  that  the  whole  skull  will  be  correspondingly 
heavier  and  stronger. 

"The  process  of  evolution  may  be  assumed  to  be,  as  it  was 
by  Darwin,  very  slow,  so  that  plenty  of  time  is  allowed  to 
selection  to  produce  the  necessary  coadaptations  which  may 
be  wanting  in  the  earlier  stages  of  the  development.  In 
the  case  of  the  enlarging  of  the  stag's  antlers  there  may  have 
been  wanting  at  first  the  necessary  congenital  strengthen- 
ing of  the  neck  muscles  but  this  would  come  to  exist  through 
use.  The  effects  of  use  would  increase,  however,  only  to  a 
certain  point,  and  there  would  finally  come  a  time  when  the 


i8o  DARWINISM   TO-DAY. 

heavy  antlers  could  be  supported  only  by  those  individuals 
which  had  received  a  strengthening  of  the  neck  muscles 
through  congenital  variation.  All  others  would  be  killed  out. 

'The  already  discussed  principle  of  the  attainment  of 
selective  value  for  a  certain  advantage  by  various  means, 
comes  also  into  play  in  this  connection.  In  time  of  drouth  it 
is  important  to  the  giraffe  only  that  it  can  reach  a  certain 
height  on  the  trees;  whether  this  height  be  reached  by  the 
aid  of  a  longer  neck  or  higher  shoulders  or  a  specially 
elongate  tongue  is  indifferent.  Through  inter-breeding 
these  various  advantages  may  be  later  united.  There  is 
always  resulting,  as  Wallace  10  has  said,  'Selection  of  the 
capacities  or  qualities  resulting  from  the  infinitely  varied 
combination  of  variations  that  are  always  occurring/ 

"Recently  Weismann X1  has  presented  the  principle  of 
germinal  selection  as  explaining  coadaptive  specialisations, 
Plate's  dis-  so  tnat  ^e  *s  evidently  not  satisfied  with  the 
belief  in  Weis-  sufficiency  of  the  three  aiding  explanations 
Seminal01*  '*  already  given.  I  hold  this  germinal  selection," 
selection,  sayS  piate,  "to  be  a  false  conception,  and  there- 

fore do  not  here  refer  to  it  further.  It  will  be  discussed  in 
detail  later."  (This  later  discussion  of  Plate's  is  a  detailed 
and  effective  destructive  criticism  of  the  theory.) 

"Weismann,  in  his  'Lectures  on  the  Theory  of  Descent,' 12 

outlines  in  detail  his  theory,  proposed  several  years  before, 

that    amphimixis    (bisexual    parentage)    is    so 

Weismann's 

principle  of  widely  prevalent  in  both  the  plant  and  animal 
amphimixis,  kingdoms,  because  it  serves  as  the  spring  of 
individual  variations.  A  considerable  part  of  the  chromo- 
somes of  the  egg-cell  is  removed  by  the  discharge  of  the 
polar  bodies,  and  the  same  results  from  the  reduction  divi- 
sions of  the  sperm-cells.  By  this  the  possibility  is  created 
of  producing,  through  the  fusion  of  the  germ-cells,  very 
various  combinations  of  the  hereditary  tendencies  and,  there- 
fore, an  actual  high  degree  of  variability  in  the  offspring. 


DARWINISM   DEFENDED.  181 

'Because  in  each  reducing  division  of  the  germ-cells  their 
ids  are  lessened  by  one-half,  the  possibility  exists  of  gradu- 
ally removing  from  the  germ-plasm  of  the  species  the  ids  of 
the  disadvantageous  variations,  for  in  each  generation  the 
offspring  of  the  disadvantageous  id  combinations  are  ex- 
tinguished [by  selection],  so  that  from  generation  to  gen- 
eration the  germ-plasm  gradually  becomes  purified  of  the 
disadvantageous  ids,  while  the  favourable  combinations 
which  amphimixis  produces  are  retained,  and  there  finally 
remain  only  the  advantageously  varying  combinations  or,  at 
any  rate,  those  in  which  the  advantageously  varying  deter- 
minants are  in  the  majority  and  therefore  have  the  most 
influence'  (Vol.  II,  p.  222).  This  conception  of  the  sig- 
nificance of  the  reduction  divisions  of  the  maturing  germ- 
cells  and  their  fusion  is  very  suggestive,  and,  theoretically, 
there  is  little  to  be  objected  to  in  the  idea  that  the  differences 
thus  created  can  be  used  by  personal  selection  for  the  pro- 
duction of  harmonious  coadaptations.  Indeed,  with  this 
explanation  in  hand,  it  is  obvious  that  the  theory  of  germinal 
selection  is  superfluous  for  the  explanation  of  coadaptations 
if  we  may  assume  that  there  is  always  a  great  mass  of 
material  in  the  individual  variations,  for  the  possibility  of 
varying  combinations  of  these  requires  no  further  expla- 
nation." 

For  the   most  part   it   is  obvious   that   Plate,  and   with 

him    other    fair-minded    Darwinians,    recognise    fully    the 

Plate  recog-     cogency  of  the  objections   against  Darwinism 

nises  the  weight  based  on  the  inutility  of  slight  variations,  on 

of  certain  objec-      .  . 

tions  to  Darwin-  tne  occurrence  and  persistence  of  hosts  of 
ism>  trivial  or  indifferent  species  differences,  and 

on  the  difficulties  presented  by  the  demands  of  a  controlled 
appearance  of  variations  necessary  to  the  development  of 
coadaptive  structures  and  functions,  so  that  they  are  inclined 
to  make  the  concessions  which  I  have  referred  to  in  the 
beginning  (chapter  vi)  of  this  presentation  of  "Darwinism 


182  DARWINISM   TO-DAY. 

Defended."  With  these  concessions  made  it  is  necessary  to 
call  to  the  aid  of  the  selection  theory,  if  it  is  still  to  be  con- 
sidered an  important  factor  in  species-forming — these  con- 
cessions do  not,  of  course,  invalidate  the  claims  of  selection 
to  be  the  all-important  final  factor  in  determining  the 
general  course  of  evolution,  by  encouraging  or  restraining 
the  various  general  lines  of  descent — certain  auxiliary  and 
aiding  theories  or  explanations.  Such  helps  to  selection  are 
to  be  found  especially  in  isolation,  organic  selection,  and 
the  Weismannian  theories  of  panmixia  and  germinal  selec- 
tion. The  outlining  of  these  theories  will  form  the  con- 
tents of  our  next  chapter. 

APPENDIX. 

1  Plate,  Ludwig,  "Uber  die  Bedeutung  der  Darwin'schen  Selec- 
tionsprinzip,"  1903. 

2  The  question,  what  is  meant  by  "selective  value,"  has  been  dis- 
cussed by  Conn  ("Method  of  Evolution,"  pp.  83-86,  1900),  as  fol- 

Conn's discus-  lows:  "How  useful  must  a  character  be  to  be  of 
sioii  of  selective  selective  value?  Such  a  question  it  is,  of  course,  im- 
value,  possible  to  answer.  The  preservation  of  any  particu- 

lar character  is  not  an  isolated  matter.  It  is  not  single  characters 
that  are  preserved,  but  a  combination  of  many  characters  together. 
The  survivor  is  the  animal  showing  the  best  combination  of  char- 
acters. It  may  even  have  some  harmful  ones,  provided  the  useful 
ones  predominate.  The  rattle  of  the  rattlesnake  has  at  times  doubt- 
less been  of  a  disadvantage  to  its  possessor,  and  has  caused  the 
death  of  hundreds  of  thousands  of  individuals.  It  is  doubtless 
possible  to  show,  as  Darwin  did,  that  it  has  also  been  of  value  to 
the  animals.  But  how  are  we  to  decide  whether  its  use  or  dis- 
advantage is  the  greater,  except  by  the  theoretical  conclusion  that 
it  must  on  the  whole  be  useful  or  it  would  have  been  eliminated? 
The  whole  study  of  utility  is  sure  to  result  in  an  unsatisfactory 
circular  logic,  something  as  follows :  The  survival  of  the  fittest  is 
a  law.  If  an  organ  be  not  useful  it  could  not  have  been  developed 
by  natural  selection.  Therefore,  all  organs  and  all  characters  must 
be  useful.  Since  in  such  a  problem  no  one  can  prove  a  negative, 
this  position  cannot  be  disproved;  but  it  is  certainly  not  very  satis- 
factory. 


DARWINISM   DEFENDED.  183 

"But  with  all  this  criticism  of  utility  it  must  be  recognised  that 
the  agency  of  utility  as  determining  survival  is  becoming  more 
significant  as  discussion  proceeds.  We  have  seen  that  it  must  be 
admitted  that  all  characters  to  be  affected  by  the  principle  of 
survival,  must  have  selective  value:  i.  e.,  must  affect  the  matter  of 
life  and  death.  But  this  demand  does  not  prove  to  be  so  serious 
when  we  recognise  that  natural  selection  works  upon  general 
averages  rather  than  individuals.  Those  who  find  the  selection 
principle  such  a  great  factor  insist  that  all  characters  have  selective 
value  if  they  have  any  -value  at  all.  If  a  character  has  the  value 
of  even  rendering  its  possessor  a  little  more  comfortable,  they  tell 
us  it  will  eventually  be  subject  to  the  principle  of  survival  at  the 
expense  of  non-favoured  animals.  The  substitution  of  old  types 
by  new  ones  is  not  a  matter  of  a  single  generation,  but  many 
generations.  In  such  a  long  history  there  must  be  innumerable 
conditions  where  any  character,  even  the  slightest,  may  have  been 
of  use  enough  to  give  its  possessors  an  advantage  over  others.  It 
is  not  necessary  to  believe  that  a  character  should  preserve  its 
possessor,  while  all  non-favoured  individuals  perish,  in  order  to 
consider  that  the  character  has  selective  value.  Considering  that 
the  origin  of  species  is  a  matter  extending  over  hundreds  of  years 
and  many  generations,  even  little  things  will  count  in  the  long  run. 
If  an  animal  has  a  slight  advantage  over  another,  which  simply 
gives  it  more  comfort  and  enables  it  to  obtain  its  food  with  a  little 
less  exertion,  this  may  tell  permanently  in  the  struggle,  since  such 
an  individual  will  have  more  energy  to  put  into  reproduction,  and 
hence  may  leave  a  larger  number  of  offspring.  The  other  non- 
favoured  individuals  may  not,  indeed,  be  exterminated  without  off- 
spring, but  may  simply  produce  less  offspring.  In  this  struggle  for 
permanency,  the  individuals  which  have  the  largest  number  of 
offspring,  other  things  being  equal,  will  inevitably  come  out  ahead, 
and  the  others  in  time  disappear. 

"An  example  will  make  this  clearer.  A  difference  of  an  inch  or 
two  in  the  length  of  a  cow's  tail  seems  a  matter  decidedly  too 
small  to  base  the  selection  principle  upon.  Can  it  be  imagined 
that  the  lengthening  of  the  tail  by  a  couple,  of  inches  can  be  of 
selective  value?  Can  we  honestly  believe  that  these  two  inches  will 
determine  that  the  longer-tailed  cow  will  live  and  produce  off- 
spring, while  the  shorter-tailed  individuals  will  die?  Only  thus, 
however,  can  we  assume  that  the  tail  has  been  developed  by  natural 
selection.  Now  this  example,  which  seems  to  be  an  extreme  case 
of  slight  utility,  may  show  us  how  it  is  possible,  upon  the  principle 
of  the  selection  of  averages,  -to  conceive  that  characters  of  slight 
use  may  be  preserved  by  natural  selection.  It  is  not  necessary  to 


184  DARWINISM   TO-DAY. 

suppose  that  the  long-tailed  individuals  are  preserved  by  this  extra 
couple  of  inches  at  the  expense  of  the  shorter-tailed  individuals 
in  order  that  the  character  may  be  within  the  reach  of  natural 
selection.  If  the  animals  are  troubled  by  insect  pests,  it  is  cer- 
tainly a  matter  of  convenience  to  them  to  have  a  tail  long  enough 
to  brush  off  the  flies,  and  the  longer  tail,  within  certain  limits,  will 
be  more  useful  than  a  shorter  one.  It  is  not  likely  that  this  will 
preserve  the  life  of  a  single  individual,  but  it  will  follow  that  the 
animals  with  longer  tails  will  be  less  irritated  by  insects  than 
those  with  shorter  tails.  Now,  although  this  would  not  affect  the 
matter  of  life  and  death,  a  nervous  irritation  would  pretty  surely 
interfere  with  the  reproductive  efficiency.  An  animal  that  is  con- 
stantly bothered  by  insects  will  have  less  nervous  energy  to  devote 
to  reproduction,  and,  therefore,  such  a  constantly  irritated  animal 
would  be  likely  to  be  somewhat  less  prolific  than  one  less  irritated. 
From  this  it  would  follow  that  the  half  of  the  animals  with  tails  a 
little  longer  than  the  average,  would  be  pretty  sure  to  leave  a  some- 
what larger  number  of  offspring  than  the  half  whose  tails  were 
below  the  average.  But  a  slightly  increased  fertility  of  this  sort 
would,  in  the  course  of  a  few  generations,  see  the  long-tailed  animals 
becoming  more  and  more  numerous,  until  they  would  eventually 
replace  the  others." 

8  Dodel-Port,  A.,  "Wesen  und  Begriindung  der  Abstammungs- 
und  Zuchtwahl-Theorie  in  zwei  gemeinverstandlichen  Vortragen," 
1877. 

4  The  tsetse-fly  (Glossina  sp.),  long  notorious  as  a  terrible 
pest  of  cattle  in  Africa,  produces  its  ravages  by  disseminating 
(through  biting,  •;.  e.,  puncturing  the  skin)  the  specific  causes 
(certain  minute  blood-inhabiting  parasitic  one-celled  animals 
known  as  trypanosomes)  of  the  plague  called  Nagana  (fly  dis- 
ease). 

6  For  an  elaborate  discussion  of  the  principle  of  correlation   (not 
bearing  perhaps  except  in  a  general  way  on  the  point  just  at  issue. 
References  to     but  of  much  general  interest)   see  Radl,  Em.,  "Uber 
papers  on  cone-    die   Bedeutung  des   Prinzips  von   der   ^Correlation   in 
lation.  der    Biologic,"    Biol    Centralbl,    Vol.    XXI,    pp.    401- 

416,  490-496,  550-56o,  605-621,  looi.  See  also  Webber,  H.  J.,  "Cor- 
relation of  Characters  in  Plant-Breeding,"  Proc.  Amer.  Breeders' 
Assoc.,  Vol.  II,  pp.  73-83,  1906. 

'  For  examples  see  R.  Meldola,  "The  Utility  of  Specific  Char- 
acters and  Physiological  Correlation,"  Proc.  Ent.  Soc.,  London,  pp. 
62-92,  1896;  also  A.  R.  Wallace,  "The  Problem  of  Utility;  are 
specific  characters  always  or  generally  useful?"  Jour.  Linn.  Soc.,. 
Vol.  XXV,  pp.  481-496,  1894. 


DARWINISM    DEFENDED.  '85 

7  Dohrn,  Anton,  "Der  Ursprung  der  Wirbeltiere  urrd  das  Princip 
des  Functionswechsel,"  1875. 

8  Cope,    E.    D.,   'The    Energy   of   Evolution,"   Amer.   Nat.,   VoL 
XXVIII,  p.  205,  1894.     I  quote  the  following:  "In  considering  the 

dynamics  of  organic  evolution,  it  will  be  convenient 
Cope's  proof          J  ,   .  . 

that  natural         to   commence   by   considering  the   claims   of   natural 

selection  cannot  selection  to  include  the  energy  which  underlies  the 
make  new  char-  process.  That  natural  selection  cannot  be  the  cause 
acters,  Q£  ^  origm  of  new  characters,  or  variation,  was 

asserted  by  Darwin,*  and  this  opinion  is  supported  by  the  following 
weighty  considerations. 

"(i)  A  selection  cannot  be  the  cause  of  those  alternatives  from 
which  it  selects.  The  alternatives  must  be  presented  before  the 
selection  can  commence. 

"(2)  Since  the  number  of  variations  possible  to  organisms  is 
very  great,  the  probability  of  the  admirably  adaptive  structures 
which  characterise  the  latter  having  arisen  by  chance  is  extremely 
small. 

"(3)  In  order  that  a  variation  of  structure  shall  survive,  it  is 
necessary  that  it  shall  appear  simultaneously  in  two  individuals  of 
opposite  sex.  But  if  the  chance  of  its  appearing  in  one  individual 
is  very  small  the  chance  of  its  appearing  in  two  individuals  is 
very  much  smaller.  But  even  this  concurrence  of  chances  would 
not  be  sufficient  to  secure  its  survival,  since  it  would  be  immediately 
bred  out  by  the  immensely  preponderant  number  of  individuals 
which  should  not  possess  the  variation. 

"(4)  Finally,  the  characters  which  define  the  organic  types,  so 
far  as  they  are  disclosed  by  palaeontology,  have  commenced  as 
minute  buds  or  rudiments,  of  no  value  whatsoever  in  the  struggle 
for  existence.  Natural  selection  can  only  effect  the  survival  of 
characters  when  they  have  attained  some  functional  value. 

"In  order  to  secure  the  survival  of  a  new  character,  that  is,  of 
a  new  type  of  organism,  it  is  necessary  that  the  variation  should 
appear  in  a  large  number  of  individuals  coincidentally  and  suc- 
cessively. It  is  exceedingly  probable  that  that  is  what  has  occurred 
in  past  geologic  ages.  We  are  thus  led  to  look  for  a  cause  which 
affects  equally  many  individuals  at  the  same  time,  and  continuously. 
Such  causes  are  found  in  the  changing  physical  conditions  that  have 
succeeded  each  other  in  the  past  history  of  our  planet,  and  the 
changes  of  organic  function  necessarily  produced  thereby." 

9  Piepers,  M.  C,  "Thesen  iiber  Mimikry,"   Verh.  Internat.  Zool. 
Cong.,  p.  350,  1902. 

*  "Origin  of  Species,"  ed.  1872,  p.  65. 


i86  DARWINISM   TO-DAY. 

10  Wallace,  A.  R.,  "Are  Individually  Acquired  Characters  Inher- 
ited?" Fortnightly  Review,  Vol.  LIII,  pp.  490-498,  1893. 

11  Weismann,    A.,    "Uber    Germinal-Selection,"     Verh.    Internat. 
Zool.  Cong.,  1896. 

12  Weismann,  A.,  "Vortrage  iiber  Descendenztheorie,"  2.  vols.,  1902. 


CHAPTER  VIII. 

OTHER  THEORIES  OF  SPECIES-FORMING  AND 
DESCENT :  THEORIES  AUXILIARY  TO  SELEC- 
TION. 

To  be  considered  now  are  two  categories  of  (mostly) 
post-Darwinian  theories,  viz.,  those  which  have  been  offered 
Classification  as  alternative  theories  intended  to  replace  more 
'of  other  theories  or  less  nearly  entirely  the  selection  theories, 
aJterMthTtT  an(^  those  other  theories  intended  to  serve  as 
selection,  auxiliary  and  supporting  theories  for  Darwin- 

ism. Obviously  these  two  kinds  of  theories  l  emanate  from 
the  two  opposing  biological  camps.  Several  of  these  alter- 
native and  auxiliary  theories  of  species-forming  have  been 
referred  to  incidentally  in  the  preceding  two  chapters,  for 
the  replacing  theories  constitute  part  of  the  strength  of 
the  anti-Darwinians,  while  the  supporting  theories  are  dis- 
tinctly relied  on  to  help  maintain  the  Darwinian  front.  The 
present  chapter,  then,  is  mostly  a  continuation  of  the  pres- 
entation of  "Darwinism  Attacked"  and  "Darwinism  De- 
fended," which  is  given  a  separate  place  because  of  the 
special  character  of  the  argument  with  which  it  has  directly 
to  do,  namely,  the  synthetic  or  theory-building  side,  instead 
of  the  analytic  or  theory-destroying  side,  and  because  of 
the  probable  advantage  to  the  student  and  general  reader 
wishing  to  understand  and  compare  the  general  character 
and  significance  of  the  various  new  theories  of  species- 
forming  with  whose  names,  such  as  heterogenesis,  ortho- 
genesis, metakinesis,  geographic  isolation,  biologic  isolation, 
organic  selection,  or  orthoplasy,  he  occasionally  meets  in  his 

187 


i88  DARWINISM   TO-DAY. 

general  reading.  As  directly  continuing  the  last  chapter  we 
may  consider  first  those  theories  put  forward,  chiefly  by" 
Darwinians,  as  auxiliaries  or  supports  of  the  selection 
theory.  Then  we  may  briefly  take  up  those  theories  that 
have  been  advanced,  mostly  in  recent  years,  as  more  or  less 
nearly  completely  prepared  to  replace  Darwinism  as  a  suffi- 
cient scientific  causo-mechanical  explanation  of  species- 
forming  and  descent. 

The  Weismannian  Theories  of  Panmixia  and  Germinal 
Selection.2 — Weismann  has  for  years  been  the  most  con- 
spicuous   of   the   neo-Darwinians.   that    is,    of 

Weismann's  im-    * 

portant  contrrtm-  those  who  would  free  Darwinism  from  all  taint 
tions  to  biology,  of  Lamarckism_it  should  always  be  remem- 
bered that  Darwin  was  inclined  to  attribute  some  degree  of 
influence  in  species-forming  to  the  Lamarckian  factor  of 
the  inheritance  of  individually  acquired  adaptive  charac- 
ters— and  to  make  selection  the  all-sufficient  and,  indeed, 
sole  factor  in  species-forming.  His  great  services  to  biology 
in  general  and  to  the  clearer  understanding  of  the  problems 
of  heredity  and  descent  in  particular,  are  unquestioned  and 
unquestionable.  His  careful  investigation  and  illumination 
of  the  vexed  question  of  the  inheritance  of  acquired  charac- 
ters, his  definitive  exposition  of  that  point  of  view  which 
distinguishes  sharply  in  the  individual  between  the  germ- 
plasm  (that  particular  protoplasm  in  the  body  from  which 
the  germ-cells,  eventually  new  individuals,  arise)  and  the 
soma-plasm  (that  which  develops  into,  or  gives  rise  to,  the 
rest  of  the  body),  his  development  of  the  interesting  and 
suggestive  combinations  of  fact  and  theory  designated  by 
the  phrase  names  "continuity  of  the  germ-plasm"  and  "im- 
mortality of  the  Infusoria," — these  products  of  his  investi- 
gating and  philosophising  mind  prove  him  one  of  the  ablest 
of  modern  biological  scholars.  They  also  make  him  the 
principal  present-day  champion  of  the  selection  theory.  For 
all  these  expositions  of  fact  and  theory  are  of  a  nature  to 


OTHER   THEORIES   OF   SPECIES-FORMING.        189 

enhance  the  credit  of  selection  and  to  discredit  certain  other 

species-forming  theories,  in  particular  the  only  one,  namely, 

Lamarckism,  which,  until  recently,  has  been  in 

Weismannas 

champion  of  any  real  sense  a  rival  of  Darwinism.  Against 
selection,  Weismann  then  and  against  Weismann's  re- 

modelled kind  of  Darwinism,  against  his  propaganda  of  the 
Allmacht  of  selection,  the  adherents  of  Lamarckism  and  the 
critics  of  selection  have  turned  their  sharpest  weapons.  The 
result  of  the  struggle  has  been  to  compel  Weismann  himself 
to  say :  "Although  the  principle  of  selection  appears  to  solve 
in  simplest  manner  the  riddle  of  the  fitness  (Zweckmassig- 
keit)  of  all  arising  organisms  (alles  Entstehendcn) ,  yet  it 
appears  ever  more  clearly  in  the  course  of  the  further  inves- 
tigation of  the  problem,  that  one  cannot  explain  all  with  it, 
at  least  in  its  original  limitations  (dass  man  mit  ihm,  in 
seiner  nrsprilngliche  Beschrankung,  wenigstens,  nicht 
ausreicht)" 

To  support  the  selection  theory  in  two  of  its  weakest  and 
most  criticised  places,  Weismann  has  proposed  two  striking 
auxiliary  theories,  namely,  the  Theory  of  Panmixia,  to 
explain  the  degeneration  of  functions  and  organs,  and  the 
more  recent  Theory  of  Germinal  Selection,  to  account 
for  the  now  practically  generally  admitted  existence  of 
orthogenesis  or  determinate  variation  and  evolutionary 
progress  along  fixed  lines  even  to  the  possible  final  dis- 
advantage of  the  organisms  involved,  and  to  account  for 
the  beginnings  of  variation  and  their  maintenance  until 
sufficiently  developed  to  serve  as  handles  for  selection.  The 
proposal  by  Weismann  of  the  second  theory,  that  of 
germinal  selection,  was  the  practical  admission  on  his  part 
of  the  impotence  of  selection  to  initiate  new  lines  of  develop- 
ment or  descent.  It  was  a  concession  on  Weismann's  part 
of  the  justness  of  the  demand  for  an  evolutionary  factor  to 
explain  the  beginnings  of  lines  of  development,  whether  of 
new  organs  or  new  species.  And  there  is  no  doubt  that  it  is 


190  DARWINISM   TO-DAY. 

the  most  ingenious  mechanical  explanation  yet  offered  of 
the  workings  of  such  a  factor.  Indeed,  Weismann,  with 
characteristic  ingenuity  and  capacity,  has  offered  the  be- 
lievers in  orthogenesis  that  which  they  so  far  had  not  been 
able  to  get  for  themselves,  namely,  a  possible  causo-mechan- 
ical  explanation  of  it.  It  should  be  noted  that  Roux's  theory 
of  the  battle  of  the  parts  (explained  later)  was  a  forerunner 
of,  and  undoubtedly  the  suggestion  for,  the_Jlieoxy  of 
germinal  selection. 

Familiar  to  all  students  of  biology,  and  certainly  not 
wholly  unfamiliar  to  laymen,  are  those  structures  or  parts 
in  the  body  known  variously  as  vestigial  struc- 
tures>  rudimentary  or  degenerate  organs.  The 
plain  vestigial  vermiform  appendix  in  man  is  one;  the  eye  of 
the  mole  is  another;  the  functionless  wing  of 
the  ostrich,  the  useless  fore-feet  of  a  milk-weed  butterfly, 
and  the  splint  bones  of  the  horse,  are  others.  Almost  every 
animal  kind  possesses  vestigial  organs,  and  some  kinds 
possess  very  many.  Those  in  the  human  body  make  an 
amazingly  long  list.  All  these  are  organs,  which  have  once — 
that  is,  in  ancestors  of  the  present  particular  organism 
— been  well-developed  and  probably  useful.  But  these 
organs  now  are  useless  or  even  harmful.  The  human 
appendix  vermiformis  is  harmful;  the  tiny  fore-feet  of  the 
milk-weed  butterfly  are  useless.  Why  do  animals  have 
such  vestigial  organs?  Because  they  derive  them  by  hered- 
ity from  ancestors.  But  in  these  ancestors  the  organs  were 
well  developed  and  useful.  How  is  it  that  the  present 
organisms  do  not  need  the  same  organs  ?  They  have  adopted 
new  habits,  or  live  in  a  new  environment,  or  have  developed 
other  means  of  supplying  the  old  want ;  in  a  word  the  organs 
are  superfluous.  How  is  it  that  the  organs  have  become 
thus  degenerate  or  vestigial?  This  is  the  question  that 
selection  has  difficulty  in  answering  satisfactorily.  Selec- 
tion can  develop  and  specialise  organs  of  use  and  advantage ; 


OTHER   THEORIES   OF   SPECIES-FORMING.        IQB 

but  how  can  it  cause  organs  no  longer  useful  and  advan- 
tageous to  degenerate? 

It  is  possible,  perhaps,  to  explain  the  eradication  of 
positively  harmful  organs  by  a  process  of  negative  or 
reversed  selection.  If  an  organ  becomes  actually  harm- 
ful because  of  a  change  in  life  conditions,  individuals 
with  the  organ  in  poorest,  least  energetically  functioning 
condition  might  be  conceived  to  have  an  advantage  and  be 
preserved  by  selection  to  pass  on  to  their  offspring  this 
less  developed,  i.  e.,  rudimentary  or  vestigial,  character  of 
the  particular  organ  in  question.  But  when  the  organ  is 
simply  only  rendered  useless  by  the  change  in  life  condi- 
tions, as  when  a  species  of  fish  or  insect  gradually  comes  to< 
inhabit  deep 'dark  caves  and  thus  has  no  more  use  for  its 
eyes,  how  does  selection  explain  the  degeneration  ?  It  really 
doesn't,  satisfactorily.  So  Weismann  offers  the  theory  of 
panmixia  to  account  for  it.  This  is,  simply,  that  owing  to 
the  cessation  of  selection  in  regard  to  the  particular  organ 
whose  function  is  rendered  no  longer  advantageous  or 
necessary  under  the  new  life  conditions — that  this  cessation 
of  selection  is  an  obvious  result  of  such  a  state  of  affairs 
was  recognised  by  Darwin  himself,  and  by  other  biologists — 
individuals  born  with  this  organ  defective  or  in  a  condition 
below  the  average,  would  not  be  necessarily  killed  by  the 
rigours  of  the  intra-specific  struggle,  and  would  therefore  be 
as  likely  to  mate  and  keep  on  producing  offspring  as  the 
ones  with  the  organ  in  average  or  above  average  conditions. 
This  general  participation  of  all  kinds  of  individuals  (all 
kinds,  that  is,  as  regards  the  state  of  the  particular  organ) 
in  producing  the  next  generation,  and  the  continued  repeti- 
tion of  this  general  mixing,  panmixia,  would  obviously  lead 
to  a  reduction  of  the  earlier  high  condition  of  development 
of  the  organ.  Weismann  thinks,  or  thought,  it  would  lead 
to  a  steady  degeneration  of  the  organ.  But  few  other  biol- 
ogists, even  those  ardent  selectionists  anxious  to  find  in 


192  DARWINISM   TO-DAY. 

panmixia  an  explanation  not  involving  the  admission  of 
any  new  organ-modifying  factor,  have  been  able  to  see  how 
panmixia  can  do  more  than  simply  reduce  the  organ  to  a 
certain  stage  below  the  original  state  of  greatest  effective- 
ness. By  resorting  to  mathematics  several  writers  have 
determined  the  exact  —  unfortunately  for  their  convincing 
character  —  several  degrees  of  reduction  or  degeneration  that 
will  result  from  panmixia.  The  difficulty  of  explaining 
degeneration  (to  the  degree  in  which  it  is  manifest  in  thou- 
sands of  known  cases)  on  the  basis  of  panmixia  alone,  is  that 
there  is  included  no  factor  or  influence  that  would  sum  up 
or  cumulate  variations  in  a  retrogressive  direction  any  more 
than  in  any  other.  The  Darwinian  variations  of  the  use- 
less organ  would,  by  the  law  of  error,  simply  keep  the  organ, 
thus  abandoned  by  selection,  swinging  about  a  mean  but 
little  below  the  condition  possessed  by  the  organ  at  the  time 
of  its  abandonment.  If  the  organ  were  large  enough,  or  of 
a  character  whereby  it  would  entail  a  constant  considerable 
disadvantageous  expense  of  food  material  to  maintain  it, 
then  selection  might,  on  a  basis  of  an  advantageous  economy 
of  living,  tend  to  reduce  it  to  a  non-disadvantageous  size  or 
character.  But  this  disadvantage,  although  easily  presumed 
by  carrying  out  the  rigour  of  the  struggle  to  a  logical  ex- 
treme, cannot,  in  fact,  —  and  biologists  on  the  whole  admit 
this,  —  in  common  sense  be  assumed. 

Lamarckism  offers  a  perfectly  simple  and  perfectly  effect- 

ive and  satisfactory  explanation  of  vestigial  organs  and  the 

modus  of  their  degeneration.     But  to  accept  this 

ian  eation'  ™eans  to  ^^P^  the  basic  principle  of  Lamarck- 


of  vestigial         jsm>  namely,  the  inheritance  of  acquired  char- 

structures,  -  .     .  r  TTT-   •  > 

acters.  And  it  is  one  of  Weismann  s  most  con- 
spicuous positive  achievements  that  he  has  demonstrated  the 
unproved  character  of  this  theory.  Lamarckism  says  that 
the  first  fishes  to  go  into  the  dark  cave  suffered  a  partial 
individual  degeneration  of  their  eyes  through  disuse  and 


OTHER   THEORIES   OF   SPECIES-FORMING.        193 

that  this  eye  degeneration  was  inherited  by  their  young, 
whose  eyes,  already  bad,  suffered  further  degeneration  in 
their  life-time  through  disuse,  and  that  after  comparatively 
few  generations  this  cumulative  actual  morphologic  degen- 
eration through  disuse — and  we  know  that  unused  active 
organs,  as  muscles,  stimulus-perceiving  parts,  etc.,  do  actu- 
ally degenerate  in  an  individual's  life-time  through  disuse — 
would  reduce  the  eyes  to  a  very  degenerate  condition.  Other 
cases  of  degeneration,  especially  of  passive  organs  (i.  e., 
where  the  organ's  condition  was  not  so  wholly  a  function 
of  use  or  disuse,  but  of  the  direct  moulding  influence  of 
extrinsic  influences),  are  explained  by  Lamarckism  on  the 
basis  of  the  inheritance  of  the  results  of  the  direct  action 
or  influence  of  environment  on  the  organ.  For  example, 
the  gradual  disappearance  of  pigment  (blanching)  charac- 
teristic of  many  cave  animals,  would  be  explained  by  the 
absence  of  the  extrinsic  factor,  light,  which  is  necessary  to 
stimulate  pigment  production. 

In  necessarily  closing  this  all  too  brief  reference 3  to 
panmixia,  it  may  be  said  that  Weismann  himself  has  in 
recent  years  recognised  its  unconvincing  character ;  and  that 
Plate,  a  strong  upholder  of  selection,  in  a  most  careful 
weighing  of  panmixia,  finds  it  capable  of  explaining  func- 
tional degeneration  but  not  any  actual  considerable  mor- 
phological rndimentation. 

The  Theory  of  Germinal  Selection  was  proposed  by  Weis- 
mann in  1895,  more  definitively  in  1896.     Plate  introduces 
Weismann's      ^*s  discussion  °f  this  theory  as  follows :  "Its 
theory  of  ger-      aim  is  the  rehabilitation  of  the  selection  princi- 
minal  selection,        ,         T,     ,     n  ,«     ,  .  ,    ,      ,  , 

pie.  It  shall  overcome  all  objections  and  doubts 
which  have  been  raised  against  the  selection  theory  and  shall 
act  as  the  magician's  wand  to  clear  all  difficulties  from  its 
way.  Its  strength  shall  avail  in  four  directions.  First,  it 
shall  explain  how  not  only  degeneration  (physiological)  but 
rudimentation  (morphological)  occurs  in  panmixia;  second, 


194  DARWINISM   TO-DAY. 

why  exactly  those  variations  needed  for  the  development  of 
a  certain  adaptation  appear  at  the  right  time ;  third,  how 
correlation  of  adaptation  comes  to  exist;  and  fourth,  how 
variations  are  able  to  develop  orthogenetically  along  a  defi- 
nite line,  without  depending  on  the  necessity  of  a  personal 
selection  raising  them  step  by  step."  Weismann  himself 
refers  to  the  theory  as  "a  spring  of  definitively  determined 
variation."  In  1902,  Weismann  further  applied  the  theory 
to  the  explanation  of  monsters,  and  other  cases  of  terato- 
genesis,  of  "sports"  (sudden  or  large  discontinuous  varia- 
tions), of  suddenly  appearing  sex-characters,  of  specific 
talents,  and  still  other  heretofore  unsatisfactorily  explained 
phenomena. 

In  defining  the  theory  of  germinal  selection  we  come  at 
the  very  start,  to  a  difficulty  based  on  the  fact  that  little  or 
no  reference  has  heretofore  been  made  in  this 
auTchemS81  ^ook  to  certain  various  theories  or  speculations 
structure  of  as  to  the  ultimate  structure  of  protoplasm,  espe- 
cially the  protoplasm  of  the  germ-cells.  In 
recognising  protoplasm  as  the  "physical  basis  of  life"  (Hux- 
ley's phrase),  biologists  have  naturally  tried  to  find  in 
its  actual  physical  make-up  some  clue  to  its  marvellous 
capacities.  The  highest  powers  of  our  best  microscopes, 
however,  reveal  little  more  of  this  intimate  physical  struc- 
ture than  does  our  unaided  eye.  Probably  the  colloidal  char- 
acter of  protoplasm,  that  is,  its  amorphous,  non-crystalline, 
viscous  condition,  is  the  most  important  physical  fact  about 
it  revealed  by  our  closest  examination.  But  this  apparent 
simplicity  of  physical  structure  is  very  unsatisfying  to  most 
biologists,  and  they  demand  the  assumption  of  an  extremely 
complex  structure;  a  subdivision  of  germinal  protoplasm 
into  structural  units  and  groups  of  units,  just  as  the  chemist 
assumes,  in  his  atomic  theory,  a  subdivision  of  substances 
into  molecules  and  atoms.  These  protoplasmic  units  are, 
of  course,  invisible ;  like  the  atoms,  they  are  beyond  the  see- 


OTHER   THEORIES   OF   SPECIES-FORMING.        195 

ing  of  our  microscopes.  This  nearly  unanimous  demand 
on  the  part  of  biologists  for  a  complex  physical  structure 
of  protoplasm,  depends  largely  on  the  fact  that  our  present 
knowledge  of  the  chemical  constitution  of  protoplasm  offers 
absolutely  no  explanation  of  its  capacities.  We  know  that 
protoplasm  is  composed  of  certain  familiar  elements,  pres- 
ent in  certain  proportions.  But  beyond  that  nothing;  the 
actual  chemical  relations  of  these  component  elements  are 
too  complex  for  analysis.  Besides,  certain  observations  of 
the  processes  of  protoplasmic  behaviour  suggest  strongly 
the  workings  of  a  machine  whose  effectiveness  lies  in  its 
physical  make-up.  Finally,  the  phenomena  of  heredity 
seem  to  admit  of  no  other  explanation  than  the  assumption 
of  a  composition  of  the  germinal  protoplasm  out  of  myriads 
of  structural  units  actually  representing  the  myriads  of  cells, 
or  groups  of  cells,  of  the  fully  developed  body. 

Ever  since  protoplasm  has  been  recognised  as  the  physical 
basis  of  life,  therefore,  and  ever  since  the  germ-cells  have 
been  recognised  not  to  be  miniature  men  and  women,  but, 
as  far  as  the  eye  and  microscope  go,  masses  of  primitive 
protoplasm  differentiated  only  into  cell-plasm,  nucleus,  and 
nuclear  parts  (chromosomes,  centrosomes,  nucleoli,  etc.), 
there  have  been  "atomic"  theories  of  protoplasmic  struc- 
ture. Unfortunately  for  the  standing  of  any  one  of  these 
theories,  each  working  biologist  seems  to  have  made  one 
for  himself,  so  that  instead  of  one  universally  accepted, 
hence  usable  and  useful,  atomic  or  unit  theory  such  as  the 
chemists  have — and  the  modern  physical  chemists  seem 
to  be  rebelling  even  against  that, — biology  has  had  a  host 
of  protoplasmic  unit  theories  of  which  the  one  we  have  here 
specially  to  refer  to  is  known  as  Weismann's  theory  of 
biophors  and  determinants.  Several  of  the  better  known  or 
more  ingenious  of  these  theories  are  outlined  in  very  sum- 
mary fashion  in  the  appendix  4  of  this  chapter.  What  we 
need  now  to  know  of  biophors  and  determinants  in  order  to 


196  DARWINISM   TO-DAY. 

understand  the  theory  of  germinal  selection,  is  this :  Weis- 
mann  conceives  the  protoplasm  of  the  cell  nucleus  to  be 
composed  of  units  called  biophors — these  biophors  can  also 
migrate  out  into  the  cytoplasm  surrounding  the  nucleus — 
which  are  the  bearers  of  the  individual  characters  of  the  cell. 
The  total  character  of  any  cell,  its  form,  make-up,  and  spe- 
cial properties,  is  determined  by  the  totality  of  its  biophors. 
These  biophors  are  not,  however,  such  simple  structures  as 
the  atoms  of  the  chemist ;  indeed,  they  are  to  be  looked  on  as 
super-molecules,  as  complex  groups  of  chemical  molecules, 
of  determined  character  and  arrangement.  Moreover,  as 
these  biophors  are  life-units,  they  possess  the  essential  char- 
acteristics of  life,  that  is,  the  capacity  to  assimilate  food, 
to  grow,  and  to  reproduce  themselves  by  division.  The  num- 
ber of  different  biophors  is  almost  inconceivably  enormous ; 
for  it  must  equal  the  possibilities  of  variety  in  character 
exhibited  by,  or  capable  of  being  exhibited  by,  all  the  cells 
of  the  body.  But  as  each  biophor  is  made  of  many  complex 
molecules  which  may  vary  among  themselves,  and  also  vary 
in  their  structural  relation  to  each  other  inside  the  biophor, 
it  is  not  difficult,  perhaps,  to  imagine  the  possible  variety  of 
biophors  to  be  equal  to  the  possible  variety  of  cell  char- 
acters. These  biophors  are  conceived  to  be  united  into 
fixed,  indissoluble  groups  called  determinants,  each  de- 
terminant containing  all  the  biophors  necessary  to  deter- 
mine the  whole  character  of  any  one  kind  of  cell.  Like 
the  biophors  the  determinants  can  assimilate  food,  grow 
and  multiply  by  division.  While  in  each  specialised  body- 
cell  there  needs  to  be  but  a  single  determinant,  namely, 
one  of  the  special  kind  conforming  to  the  special  kind 
of  cell,  in  the  germ-cells  there  must  be  co'nceived  to  be 
every  kind  of  determinant  which  may  be  found  in  all 
the  body-cells  taken  together.  But,  fortunately,  by  virtue 
of  the  determinants'  capacity  for  multiplication  it  is 
not  necessary  to  assume  that  there  exists  in  the  germ  a 


OTHER   THEORIES   OF   SPECIES-FORMING.        19? 

determinant  for  every  cell  that  is  to  develop  in  the  body,  but 
only  one  for  every  different  kind  of  cell;  all  cells  exactly 
alike  can  be  supplied  with  similar  determinants  by  the  multi- 
plication of  the  proper  kind.  Now  Weismann's  theory  of 
germinal  selection  rests  upon  the  assumption  of  a  competi- 
tion or  "struggle"  of  the  determinants  in  the  germ-plasm 
for  food  and  hence  for  opportunity  to  grow,  to  be  vigorous, 
and  to  multiply.  The  germ-cells  derive  their  food,  as  do 
the  other  cells  and  tissues  of  the  body,  from  the  general 
food  streams  circulating  around  and  through  the  cells. 
Weismann,  recognising  the  absolute  principle  of  slight  varia- 
tion everywhere  in  Nature, — it  is  practically  impossible  to 
conceive  of  identity, — believes  that  the  initially  slightly 
stronger  or  more  capable  determinants  will  be  able  to  take 
up  larger  supplies  of  food,  even  to  the  extent  of  lessening 
the  supply  for  neighbouring  determinants,  perhaps  to  the 
degree  of  starvation.  Indeed  he  suggests  a  reason  for  the 
initial  slight  variations  in  vigour  of  the  determinants  in  the 
probability  that  the  food  will  reach  the  various  determinants 
in  slightly,  purely  fortuitously,  variable  quantity,  so  that 
the  first  inequality  in  vigour  of  the  determinants  will  depend 
on  the  fortuitous  variability  of  food  supply,  while  there- 
after the  variability  in  the  determinants  thus  produced  will 
enable  the  stronger  ones  to  draw  to  themselves  or  take  up 
more  food  and  thus  accumulate  determinately  the  initial 
fortuitous  inequality. 

Thus  when  the  germ-cell  begins  its  development  into 
a  new  individual  those  kinds  of  cells,  tissues,  and  organs 
will  be  best  developed  whose  determinants  were  most  suc- 
cessful in  the  struggle  for  food,  while  other  parts  of 
the  body  may  be  made  smaller  or  even  may  not  appear 
at  all  because  of  the  starvation  of  the  determinants  re- 
sponsible for  the  cells  which  should  compose  them.  Also 
these  better-developed,  larger,  more  vigorous  determinants 
of  one  generation  will  hand  on  to  the  germ-plasm  of  the 


198  DARWINISM   TO-DAY. 

next  generation  strong  and  extra-vigorous  daughter  deter- 
minants. For  any  determinant  in  the  germ-plasm  of  a  fer- 
tilised egg-cell  has  not  alone  to  furnish  determinants  which 
shall  control  the  development  of  body-tissues  and  organs 
of  the  individual  which  develops  from  this  cell,  but  also  to 
furnish  daughter  determinants  for  the  new  germ-plasm  of 
this  individual.  This  will  result  in  a  repetition  of  the 
extra-development  in  the  next  generation  of  the  same  organs 
as  were  strongly  developed  in  the  first  generation,  and  the 
under-development  of  the  same  organs  as  were  weak  or 
wanting  in  the  first  generation.  Which  process  continued 
is  simply  determinate  variation,  that  is,  variation  along 
fixed  lines  without  reference  to  personal  selec- 
lectioTresnlts"  ^on-  Now  when  this  variation  becomes  so 


indeterminate  marked  that  it  is  of  life-and-death  advantage 
or  disadvantage  in  the  life  of  the  individual,  it 
will  immediately  become  subject  to  the  control  of  personal 
natural  selection,  and  under  the  influence  of  this  dominant 
factor  in  determining  adaptation,  either  be  further  fostered 
and  fixed  or  be  extinguished.  If  the  increasing  organ  or 
part  due  to  germinal  selection  be  one  whose  increase  is 
advantageous  to  the  individuals  possessing  it,  then  natural 
selection  will  preserve  those  individuals  and  the  germinal 
advantage  of  the  determinants  of  this  part  will  be  steadily 
increased,  as  the  size  and  power  of  assimilation  of  the 
determinants  correspond  to  the  size  and  vigour  of  the  part. 
By  this  theory  Weismann  believes  that  he  has  explained 
away  one  of  the  most  potent  objections  to  natural  selection, 
viz.,  that  it  is  necessary  to  assume,  for  the  effective  work  of 
selection,  the  timely  appearance  of  the  proper  variations 
necessary  for  the  continued  advantageous  modification  of 
a  part.  "'Knowing  this  factor,  we  remove,  it  seems  to  me," 
writes  Weismann,8  "the  patent  contradiction  of  the  assump- 
tion that  the  general  fitness  of  organisms  or  the  adaptations 
necessary  to  their  existence,  are  produced  by  accidental 


OTHER   THEORIES   OF   SPECIES-FORMING.        199 

variations — a  contradiction  which  formed  a  serious  stum- 
bling-block to  the  theory  of  selection.  Though  still  assum- 
ing that  primary  variations  are  'accidental/  I  yet  hope  to 
have  demonstrated  that  an  interior  mechanism  exists  which 
compels  them  to  go  on  increasing  in  a  definite  direction,  the 
moment  selection  intervenes.  Definitely  directed  variation 
exists,  but  not  predestined  variation  running  on  independ- 
ently of  the  life  conditions  of  the  organism  as  Nageli,  to 
mention  the  position  that  the  most  extreme  advocate  of 
this  doctrine  has  assumed :  on  the  contrary,  the  variation  is 
such  as  is  elicited  and  controlled  by  those  conditions  them- 
selves, though  indirectly." 

Obviously  Weismann  in  his  theory  of  germinal  selection 
has  preserved  the  actuality  of  a  struggle  and  a  selection,  but 
with  a  "rehabilitation"  of  natural  selection  in  the  real  Dar- 
winian meaning  and  only  fair  application  of  the  phrase  the 
new  theory  has  nothing  to  do.  It  is,  much  more,  a  distinct 
admission  of  the  inadequacy  of  natural  selection  to  do  what 
has  long  been  claimed  for  it.  It  is  the  first  serious  attempt 
at  a  causo-mechanical  explanation  of  a  theory  of  ortho- 
genesis, that  is,  variation  along  determined  lines. 

As  to  our  acceptance  or  non-acceptance  of  such  a  theory 
we  need  say  little.  It  consists  of  two  purely  speculative  basic 
assumptions :  First,  Weismann's  particular  theory  of  the 
ultimate  structure  of  the  germ-plasm,  namely,  the  theory  of 
biophors  and  determinants ;  and  secondly,  the  assumption 
that  there  is  a  struggle  for  food  among  the  determinants. 
There  is  no  proof  of  pure  observation  or  experiment  for 
the  theory,  and  there  is  some  proof  directly  against  it.  And 
yet  the  great  need  of  a  working  hypothesis  for  the  causo- 
mechanical  explanation  of  determinate  variation  makes  us 
give  such  a  pure  speculation  more  attention  than  it  might 
otherwise  get.  Unfortunately  the  attention  thus  given  to 
this  particular  theory  seems  to  have  resulted  in  the  bringing 
forward  of  some  rather  serious  objections  to  the  possibility 


200  DARWINISM   TO-DAY. 

of  the  truth  of  the  theory.  A  few  of  these  objections  6  may 
be  briefly  stated. 

According  to  the  theory  there  should  be  plainly  exhibited 
in  the  variation  of  any  species,  decided  tendencies  in  certain 
Objections  to  specific  directions.  In  all  species,  in  all  indi- 
mtoafselJcT"  viduals,  the  struggle  of  the  determinants  must 
tion.  result  in  the  suppression  or  reduction  of  some, 

the  extra-development  of  others.  Thus  variation  should 
not  reveal  itself  according  to  the  law  of  error,  that  is,  should 
not  be  distributed  normally  about  a  mean  or  mode.  But 
that  is  exactly  the  condition  of  variation  in  a  majority  of 
those  cases  in  which  the  variation  of  one  or  more  organs 
in  any  species  has  been  statistically  studied.  The  plotted 
curve  of  any  particular  variation  of  this  type  is  a  symmetri- 
cal curve  nearly  coincident  with  the  theoretical  one  express- 
ing the  law  of  error  for  the  same  case. 

The  constancy  of  species  is  just  as  marked  and  actual  a 
condition  as  the  condition  of  slight  fluctuating  variations 
inside  the  species.  This  constancy  is  steadfast  for  con- 
siderable time-periods.  But  with  such  an  active  orthogene- 
sis as  the  theory  of  germinal  selection  provides,  there  could 
be  no  such  steadfast  constancy.  Weismann  himself  recog- 
nised the  weight  of  this  objection  to  the  theory,  and  speaks 
of  an  attribute  of  "self-correction"  pertaining  to  the  germ- 
plasm,  which  shall  regulate  or  check  too  rapid  an  ortho- 
genetic  development. 

The  actual  change  of  the  competitive  determinants  due 
to  their  obtaining  an  over  or  under  supply  of  food  should 
be  one  simply  quantitative  in  degree;  such  germinal  selec- 
tion could  thus  lead  to  the  change  in  size  and  strength  of 
organs  already  present  in  the  species,  but  could  offer  no 
explanation  of  qualitative  changes,  i.  e.,  the  appearance  of 
new  kinds  of  structures.  Moreover,  even  in  cases  of  purely 
quantitative  change,  such  familiar  cases  as  the  persistence 
through  long  time-periods  of  small,  rudimentary  organs, 


OTHER   THEORIES   OF    SPECIES-FORMING.        201 

without  any  indication  of  further  reduction,  indicate  a  pecu- 
liar cessation  in  the  forthright  working  of  germinal  selec- 
tion. Why  should  not  the  weak  determinants  of  these  weak 
organs  go  completely  to  ground  in  the  struggle  ? 

Actual  experimentation  on  the  influence  of  food-supply 
in  development  does  not  bear  out  the  assumption  on  which 
the  theory  of  germinal  selection  rests.  Weismann  himself 
gave  the  larvae  of  flies,  and  I  have  given  the  larvae  of  silk- 
worms through  their  whole  life-time,  an  abnormally  small 
food  supply  (in  the  case  of  the  silkworms  this  supply  was 
from  one-fourth  to  one-eighth  the  amount  normally  eaten 
by  full-fed  larvae),  with  the  only  result  that  the  mature- 
individuals  were  dwarfed ;  that  all  their  parts  were  reduced 
in  size,  but  the  actual  size  proportions  of  the  various  organs 
and  parts,  and  their  relations  to  each  other,  were  unchanged. 
The  determinants  seemed  to  share  equally  the  hardships  of 
short  rations  rather  than  a  few  of  the  stronger  getting  the 
better  of  the  weaker.  From  the  eggs  of  birds  considerable 
quantities  of  yolk  have  been  withdrawn  without  modifying 
appreciably  the  individuals  developed  from  the  eggs. 

If  the  struggle  of  the  determinants  is  really  an  actual  and 
severe  one  then  only  those  of  the  large  strong  organs  should 
survive,  all  the  others  being  starved  out.  Such  a  condition 
would  result  in  the  exclusive  development  of  monsters,  i.  e.,. 
individuals  lacking  numerous  organs  (the  small  ones),  and 
with  the  large  ones  all  over-developed. 

Roux's  Theory  of  Intra-selcction  or  the  Battle  of  the 
Parts. — Distinctly  more  likely  to  appeal  to  our  reason  is  the 
theory  of  Roux,7  proposed  in  1881,  to  explain  how  one  or 
more  organs  may  exhibit  a  progressive  development  or 
increase  in  size  and  capacity  without  reference  to  natural 
selection  and  also  to  account  for  the  many  remarkable  adap- 
tations of  slight  and  delicate  but  extremely  precise  character 
exhibited  by  various  internal  organs.  Roux  made,  however, 
a  too  radical  distinction  between  external  or  superficial 


202  DARWINISM   TO-DAY. 

adaptations  on  the  one  hand,  attributing  these  to  the  influ- 
ence of  natural  selection,  and  the  adaptations  of  internal 
parts  on  the  other,  which  he  would  attribute  to  the  influ- 
ence of  his  functional  stimuli  and  of  his  struggle  among 
the  inner  parts  of  the  body.  This  struggle,  like  that  among 
Weismann's  hypothetical  determinants,  is  one  chiefly  for 
food,  but  in  Roux's  theory  there  is  no  assumption  of  hypo- 
thetical life  units,  nor  any  lack  of  clearness  concerning  the 
initiation  of  the  actual  struggle.  The  competing  parts  in 
Roux's  theory  are  the  chemical  molecules  composing  the 
The  competing  cell>  the  cells  themselves,  groups  or  tissues  of 
parts  in  Roux's  cells,  and  even  whole  organs.  The  spurs  to  the 

theory  are  actu-  .  .  .          f       ,  .  ,         .        , . 

ally  recognised  competition  for  food  are  functional  stimuli, 
structures.  whose  result  is  to  set  up  a  special  demand  and 
necessity  for  more  food.  Roux's  classic  example  will  make 
this  clear.  It  is  a  matter  of  fact  that  the  fine  plates  and 
layers  of  bone  in  the  "spongy  tissue"  of  the  long  bones  of 
the  body,  are  so  disposed  as  actually  best  t6  withstand  the 
stresses  most  usually  brought  to  bear  on  the  bones.  Thus 
they  show  a  fine  adaptation  of  arrangement,  which  one  meets 
difficulties  in  trying  to  explain  as  due  to  natural  selection. 
For,  if  we  imagine  the  thin  plates  of  the  spongy  tissue 
purely  miscellaneously  arranged,  the  possible  slight  varia- 
tions whereby  a  few  plates  at  a  time  might  fortuitously 
occur  in  a  position  or  direction  better  fit  to  strengthen  the 
whole  bone,  are  so  insignificant  in  proportion  to  the  condi- 
tion throughout  all  the  rest  of  the  bone  that  we  cannot  possi- 
bly attribute  to  them  a  life-and-death  value  in  the  individual's 
struggle  for  existence.  Roux  assumes  that  the  stresses 
brought  to  bear  on  the  bone  during  its  development  act  as 
functional  stimuli  to  all  those  plates  in  the  forming  spongy 
tissue,  which  lie  in  such  places  or  at  such  an  angle  to  the 
stress  as  to  be  affected  by  them,  and  in  response  to  these 
stimuli,  which  in  Roux's  belief  are  necessary  to  the  normal 
structural  development  and  maintenance  of  any  part,  these 


OTHER   THEORIES    OF    SPECIES-FORMING.        203 

forming  bony  plates  will  take  up  more  food  than  the  un- 
stimulated  ones,  and  thus  will  be  developed  at 
the  exPense  of  these  others-  Similarly  with 
all  those  other  marvellously  delicate  inner  adap- 
tations of  fine  and  minute  and  oft-repeated  structures  to  the 
special  functions  of  the  organs  containing  these  structures. 
The  stimulus  of  the  function  excites  a  trophic  demand  on 
the  part  of  the  struggle  and  an  actual  capacity  for  satisfying 
the  demand,  that  soon  leads  to  the  extra-development  of 
the  stimulated  parts  at  the  expense  of  adjacent  similar  parts 
deriving  food  from  the  supply  common  to  all.  Thus  Roux 
would  explain  the  exquisite  adaptation  of  the  arrange- 
ment of  the  muscle-fibres  in  the  walls  of  the  blood-vessels, 
the  taenidia  or  spiral  threads  in  the  tracheae  of  insects,  the 
little  barbs  on  the  feathers  of  birds  which  hold  these  feathers 
together  in  almost  air-tight  continuity,  the  numerous  protect- 
ive hairs  covering  the  spiracles  of  many  insects,  etc.,  etc. 

It  will  be  noted  that  the  competition  of  the  parts  is  really 
twofold ;  thus,  while  for  successful  development  it  is  neces- 
sary for  parts  to  be  successful  in  food-getting, 

The  struggle        ,  /  .      • 

of  the  parts  is  this  success  in  food-getting  seems  to  depend 
twofold,  upon  the  prerequisite  of  receiving  a  needed 

functional  stimulus.  Thus  there  may  be  said  to  exist  a  com- 
petition for  functional  stimuli.  But  obviously  success  in 
this  competition  depends  chiefly  on  the  hazard  of  position. 
Those  plates  in  the  forming  spongy  tissue  of  a  long  bone 
which  happen  to  lie  where  the  stress  comes,  and  in  a  special 
direction  to  be  affected  by  it,  are  the  winners  in  the  compe- 
tition for  stimuli. 

Roux's  theory  has  appealed  strongly  to  many  biologists, 
but  others  have  rejected  it  wholly,  or  at  least  as  an  explana- 
tion of  fine  inner  adaptations.     Plate  takes  this 

Plate's  criti-  .  .  r 

cism  of  Eoux's  latter  position,  but  finds  a  great  service  in  the 
theory,  theory  in  that  "Roux  has  given  in  it  a  profound 

analysis  of  the  well-known  fact  that  use  strengthens  and 


204  DARWINISM   TO-DAY. 

disuse  weakens.  His  is  the  great  merit  of  having  clearly 
explained  the  extraordinary  importance  (Tragwcite),  in  the 
building  of  new  forms  and  adaptive  structures,  of  this  ele- 
mentary attribute  of  organisms.  We  have  to  thank  him  for 
the  best  putting  together  of  all  those  observations  which 
permit  of  but  the  one  conclusion,  that  the  functional  stimuli 
exercise  a  trophic  activity,  that  is,  that  each  organ  by  the 
constant  exercise  of  its  function  becomes  stimulated  to 
stronger  assimilation  and  increased  multiplication  of  its 
elementary  parts,  and  that  out  of  this  there  results  a  height- 
ened functional  capacity."  However,  as  Plate  points  outr 
The  law  of  tms  "^aw  °f  functional  adaptation"  does  not 
functional adap-  appiy  to  an  organs  and  tissues;  "the  teeth  of 

tation  does  not 

apply  to  all  many  mammals  become  impaired  through  con- 
organs,  stant  use,  and  most  of  the  sense-organs  are 
apparently  not  bettered  through  use  in  regard  to  their  per- 
ceiving elements  but  only  in  regard  to  their  carrying  ele- 
ments. Every  exercise  is  followed  by  a  certain  fatigue 
which,  in  cases  of  exhaustion,  is  greater  than  the  aimed  at 
(ergielte)  increase  of  functional  capacity.  Also  the  trophic 
stimulation  can,  in  certain  cases,  lead  to  hypertrophy  and 
other  unadaptive  results."  But  as  regards  the  actual  "strug- 
gle of  the  parts,"  and  especially  as  regards  the  claim  that- 
such  a  struggle  is  to  account  for  inner  adaptations,  Plate,  as 
a  consistent  natural  selectionist,  is  wholly  sceptical.  He 
offers  five  objections  to  any  usurpation  of  the  functions  of 
natural  selection  by  this  intra-selection  theory.  First,  he 
holds,  with  Wolff,  that  it  is  impossible  to  place  the  inner 
adaptations  in  any  sharp  contrast  with  outer  adaptations. 
They  are  contrasted  only  in  that  the  former  stand  in  a  more 
indirect  relation  to  the  conditions  of  life.  Indeed  a  single 
organ,  as  a  claw  for  example,  can  show  an  external  adaptive- 
ness  in  that  it  might  be  especially  well  arranged  to  scratch 
hard  dry  ground,  and  at  the  same  time  be  distinctly  adap- 
tively  constructed  as  regards  its  fine  inner  structure.  "If 


OTHER   THEORIES   OF   SPECIES-FORMING.        205 

natural  selection,"  says  Plate,  "is  capable  of  producing  outer 
adaptations  such  as  making  the  fur  of  a  mammal  thicker 
and  thicker  as  a  protection  against  the  cold,  why  can  it  not 
increase,  or  if  advantage  lies  the  other  way,  decrease,  the 
number  of  bony  plates  in  the  spongy  tissue  of  the  long 
"bones?" 

Second,  the  capacity  of  living  substance  to  be  stimulated 
to  increased  food-getting  is  an  elementary  attribute  of  organ- 
isms just  as  the  capacities  to  assimilate,  to  be 

Trophic  stimu-  J  .   t 

lation  not  ex-  irritable,  and  to  breathe  are.  This  special 
plained.  capacity  is  not  explained  by  the  theory  of  intra- 

selection;  it  is,  indeed,  just  now  wholly  inexplicable.  One 
might  perhaps  fairly  assume  that  it  is  the  result  of  a  gradual 
development  from  the  Protozoa  onward,  through  the  influ- 
ence of  individual  selection.  But  this  is  no  explanation  of  its 
origin.  Roux,  himself,  indeed,  expressly  declares  that  he 
bases  his  theory  on  the  proved  but  not  explained  fact  of 
functional  adaptiveness,  but  some  of  his  followers  often 
forget  this  and  seem  to  claim  that  the  distinctly  advantage- 
ous peculiarity  of  most  tissues  to  be  able  to  increase  in 
strength  and  size  through  use  is  a  direct  result  of  the 
battle  of  the  parts. 

Third,  Plate  holds  that  the  battle  of  the  parts  plays  no 
role  in  ontogeny.     The  cleavage  and  embryonal  develop- 
B  ment  are  wholly  controlled  by  heredity,  so  that 

parts  not  evident  there  is  nothing  left  for  the  battle  of  the  parts, 
in  ontogeny,  There  occurs  a  peaceful  and  regular  split- 
ting apart  of  the  single  cells  and  a  separation  of  them 
according  to  their  different  qualities,  and  it  does  not  at  all 
•occur  that  the  strongest  cells  get  all  the  food  and  the  weak- 
est none,  but  on  the  contrary  each  receives  as  much  as  it 
needs  for  its  growth.  In  a  blastula  of  thirty-two  cells  it  is 
not  the  capacity  on  the  part  of  certain  cells  which  results  in 
the  stronger  growth  of  some  and  the  weaker  growth  of 
others,  or  the  more  rapid  multiplication  of  some  and  the 


206  DARWINISM   TO-DAY. 

less  rapid  of  others,  but,  on  the  contrary,  for  each  species 
there  is  a  definite  law  of  growth  which  we  may  only  explain 
as  the  expression  of  a  force  of  heredity,  not  capable  yet  of 
analysis.  Matters  certainly  do  not  go  on  in  an  embryo  as 
in  an  agar  culture  containing  several  kinds  of  bacteria  of 
which  only  that  one  with  the  greatest  life  force  remains. 
Were  the  development  of  the  embryo  determined  by  the 
food-zeal  of  the  cleavage  cells,  it  would  happen  that  in  a 
short  time  a  few  cells  specially  capable  of  assimilation  would 
get  the  upper  hand,  and  as  a  consequence  only  a  few  quali- 
ties be  left  to  the  embryo;  a  real  differentiation  into  thou- 
sands of  different  cell-sorts  would  not  be  possible.  All  the 
facts  of  symmetry  and  auto-regulation  in  embryonic  develop- 
ment speak  against  any  considerable  influence  of  a  battle  of 
the  parts  during  development. 

Fourth,  Plate  declares  that  in  the  acquirement  of  new 

characters  no  selective  intra-struggle  takes  place,  or  at  least 

in  only  most  insignificant  manner,  but  that  the 

the  parts  in  the    new  structures  arise  either  through  the  direct 

acquirement  of     influence  of  new  stimuli  or  by  natural  selection 

new  characters,        ,.  .    . 

of  new  germinal  variations  of  unknown  origin. 
In  the  first  place  it  is  simply  the  matter  of  position,  not  at 
all  that  of  quality,  that  decides  whether  the  certain  cells 
shall  be  changed  or  not.  Think,  for  example,  of  a  vessel 
in  whose  walls  the  connective  tissue  fibres  cross  and  recross 
in  all  directions  wholly  without  order,  and  conceive  that  a 
constant  or  repeated  stress  in  both  longitudinal  and  trans- 
verse directions  is  exerted  on  this  vessel.  It  would  result 
that  all  those  fibres  lying  in  the  absolute  or  approximate 
directions  of  these  stresses  would  be  most  stretched  and 
would  in  consequence  of  their  trophic  irritability  most  rapidly 
enlarge  and  increase  with  special  rapidity.  Now  by  the 
repetition  and  inheritance  of  this  result  of  use  it  would  finally 
come  about  in  the  course  of  generations  that  all  the  fibres 
situated  in  other  directions  to  the  stresses  would  die  out,. 


OTHER   THEORIES   OF    SPECIES-FORMING.        207 

and  thus  a  definite  longitudinal  and  transverse  arrangement 
of  fibres  in  the  walls  of  the  vessel  result.  Without  doubt, 
holds  Plate,  much  advance  is  won  in  this  way,  but  this 
specialisation  of  structure  is  not  a  result  of  intra-struggle 
but  rests  on  the  elementary  attribute  of  trophic  irritability. 
Not  the  best-qualified  but  the  best-situated  fibres  have  van- 
quished the  others  by  robbing  them  of  food  and  thus  finally 
destroying  them.  In  the  second  place,  "many  inner  struc- 
tures belong  to  the  great  category  of  passive  adaptations; 
they  function  only  through  their  presence  and  cannot  thus 
be  further  developed  by  use  or  disuse,  that  is,  by  functional 
stimuli,  but  only  by  natural  selection.  Here  belong,  for 
example,  the  stratification  of  the  lens  in  the  human  eye,  the 
apodemes  (inner  projections  of  the  chitinised  cuticula) 
which  protect  the  ventral  nerve-cord  of  the  crabs,  the  chitin 
hooks  which  hold  together  the  fore  and  hind  wings  of  many 
insects,  and  the  similar  structures  which  bind  together  the 
secondary  branches  of  the  feather  vanes  of  birds.  These 
inner  adaptations  cannot  have  resulted  through  the  influence 
of  light  or  of  nervous  function  or  flight.  There  is  but  one 
explanation  possible;  namely,  that  natural  selection  has 
seized  on  and  developed  fortuitously  appearing  germinal 
variations.  But  if  natural  selection  can  produce  such  inner 
adaptations  why  can  it  not  then  produce  all  the  others  ?" 

Fifth,  Plate  points  out  that  Roux's  theory  is  based  on  the 

inheritance   of    those    special   body    characters    which    are 

acquired  through  the  battle  of  the  parts — more 

Boux'stheory      rightly,  Plate  holds,  through  functional  adapta- 

is  to  accept  the     tion, — so  that  to  accept  the  theory,  one  has  to 

inheritance  of 

acquired  char-  declare,  to  that  degree,  a  belief  in  the  inherit- 
acters,  ance  of  aCqUjre(j  characters.  Thus  from  the 

start,  the  neo-Darwinians  cannot  accept  the  theory. 

After  all  what  is  this  theory  of  Roux's  but  a  refinement,  a 
special  case,  of  the  broader  and  more  general  long-known 
Lamarckian  theory  of  the  modifying  and  formative  influ- 


DARWINISM   TO-DAY. 

ence  of  use  and  disuse,  accumulated  through  inheritance? 

That  is,   if  we  accept   Plate's   analysis  that  the  theory   is 

really  not  one  of  a  battle  of  the  parts,  but  of 

The  battle  of  „ 

the  parts  theory  the  effects  of  functional  stimuli.    And  however 

of  LamarckLT  ^  proposer  of  the  theory  may  protest  against 
such  an  apparent  violent  setting  over  of  it  from 
the  category  of  selection  (Darwinian)  theories  into  that  of 
the  inheritance  of  use  (Lamarckian)  theories,  I  believe  that 
most  of  us  will  see  the  justness  of  Plate's  analysis.  I  do 
not  believe  that  Roux's  theory  in  any  way  strengthens  the 
selection  conception.  To  my  mind,  indeed,  it  is  simply  a 
concession  of  the  inadequacy  of  selection  to  initiate  adapta- 
tion, and  a  welcome  and  satisfying  explanation  of  how  such 
an  initiation  may  occur  in  many  cases,  in  certain  cases,  that 
is,  of  active  adaptations.  Plate's  argument  that  natural 
selection  must  be  the  only  explanation  for  the  cases  of 
passive  adaptations  and  hence  may  be  held  capable  for 
accounting  for  the  active  ones,  has  no  conviction  for  me,  for 
I  do  not  believe  that  natural  selection  is  the  only  possible 
explanation  of  the  passive  cases.  In  fact,  I  cannot  conceive 
it  to  be  a  possible  explanation  of  the  initiation  of  these  cases. 
And  I  am  glad  to  find  in  Roux's  theory — even  if  it  be  not 
exactly  applied  in  Roux's  own  sense — a  mechanical  expla- 
nation of  the  possibility  of  initiating  certain  fine  and  delicate 
inner  adaptations. 

Organic  Selection. — An  interesting  attempt  to  escape  from 

the  difficulties  which  are  imposed  on  one  by  an  absolute 

adherence  to  Weismann's  doctrine  of  the  impos- 

tion,  orthoplasy,   sibility  of  the  inheritance  of  acquired  characters 

or  ontogenetic  coupled  with  a  belief  in  the  inadequacy  of  the 
selection,  .  .  . 

slight  fluctuating  germinal  variations  to  afford 

handles  for  the  action  of  natural  selection,  is  the  theory  va- 
riously called  organic  selection,  or  orthoplasy,  proposed  by 
Baldwin8  and  Osborn9  in  America,  and  Lloyd  Morgan10  in 
England.  This  theory,  which  might  also  be  called  one  of 


OTHER   THEORIES   OF   SPECIES-FORMING.        209 

"ontogenetic  selection,"  or  of  ''coincident  selection,"  is  that 
the  personal  selection,  or  individual  survival,  among  indi- 
viduals of  a  species  does  not  necessarily  depend  solely  upon 
congenital  variation  but  may,  must,  indeed,  depend  on  any 
ontogenetically  acquired  adaptations  as  well.  As  in  many 
cases  these  ontogenetic  adaptations  are  considerable,  they 
will  often  carry  individuals  through  very  critical  periods  in 
their  lives.  But  the  individuals  showing  these  ontogenetic 
adaptations  in  best  degree  will  be  those  which  actually  pos- 
sess certain  slight  congenital  variations,  especially  of  the 
nervous  system  or  coordinating  nerve  centres,  "which  lend 
themselves  to  intelligent  initiative,  adaptive,  or  mechanical 
modification  during  the  lifetime  of  the  creatures  which  have 
them."  The  ontogenetic  adaptations  may  occur  regularly 
in  the  lives  of  successive  generations  of  individuals  if  the 
environment  remains  fairly  constant.  During  these  suc- 
cessive generations  the  congenital  variations  of  brain,  say, 
which  make  the  successful  ontogenetic  adaptations  possible, 
will  by  selection  of  the  best  ontogenetically  varying  individ- 
uals be  themselves  selected,  and  the  species  thus  gradually  be 
modified  in  a  determinate  direction.  Also  congenital  varia- 
tions of  nearly  the  same  nature  as  the  ontogenetic  variations, 
or  of  a  nature  to  supply  the  same  need,  will  have  time  (that 
is,  more  chance,  because  of  the  longer  time  and  repeated 
generations)  to  appear.  In  this  case  these  advantageous 
variations  can  be  transmitted  directly  by  heredity,  and  thus 
a  permanent  adaptation  be  effected  which  will  seem  to  be  the 
result  of  the  inheritance  of  an  acquired  character  (i.  e.,  the 
similar  ontogenetic  modifications)  but  which  in  reality  is 
only  the  normal  inheritance  of  a  congenital  variation. 

In  the  language  of  all  the  sponsors  for  this  theory  there 
seems  to  be  a  suggestion  of  the  piling  up  or  adding  together 
of  congenital  variations,  not  simply  those  of  brain  or  other 
control  centre  which  make  the  ontogenetic  modifications 
possible,  but  also  of  these  modifications  themselves  during  the 


210  DARWINISM   TO-DAY. 

successive  generations  through  which  the  species  is  safely 
carried  by  the  temporary  regularly  appearing  ontogenetic 
adaptations.  But  there  is  nothing  in  strict  neo-Darwinism 
to  permit  of  any  such  idea  of  increase.  Such  moving  for- 
ward without  the  aid  of  selection  can  only  be  explained  by 
the  adoption  of  some  theory  of  orthogenesis.  Either  the  con- 
genital variations  are  of  such  a  character  that  the  resulting 
ontogenetic  modifications  are  not  fairly  to  be  distinguished 
from  them,  in  which  case  they  are  assumed  to  be  large 
enough  from  the  start  to  afford  handles  for  natural  selection 
(which  the  proposers  of  the  theory  are  not  claiming),  or 
they  depend  for  their  preservation  on  a  kind  of  happy  coinci- 
dence in  occurrence  with  similar  more  effective  ontogenetic 
modifications  which  are  really  large  enough  to  save  the  life 
of  the  organism  and  hence  the  slight  congenital  variations 
along  the  same  line.  But  in  this  latter  case  organic  selection 
cannot  demand  much  discussion  until  it  explains  away  a 
Delageand  radical  failing  pointed  out  clearly  by  Delage 

Plate's  criticisms  d  pj  t  Thig  j  j  j  th  t  •  th  face  f 
of  organic  selec-  r  ' 

tion,  the  large  character  which  ontogenetic  adapta- 

tion may  and  often  does  possess,  those  individuals  in  which 
the  slight  congenital  variations  in  the  right  direction  finally 
appear  will  have  no  special  advantage  over  those  in  which 
they  do  not  appear ;  the  large  and  effective  character  of  the 
ontogenetic  adaptations,  which  are  common  to  both  kinds  of 
individuals,  being  quite  sufficient  to  determine  the  result  of 
personal  selection.  The  congenital  variations  will  be  too 
small  in  comparison  with  the  ontogenetic  variations  to  cut 
any  figure  in  the  fate  of  the  individuals,  and  there  is  no 
reason  at  all  to  believe  that  individuals  showing  the  slight 
congenital  variations  in  the  right  direction  will  be  the  only 
ones  to  show  the  saving  large  ontogenetic  adaptations. 
Plate  suggests  the  following  case  to  show  the  inutility  of 
this  theory :  Suppose  an  antelope  species  to  have  a  leg  muscle 
averaging  seven  cm.  in  thickness,  and  several  individuals  to 


OTHER   THEORIES   OF   SPECIES-FORMING.        211 

show  a  congenital  variation  bringing  the  leg  muscle  up  to 
eight  cm.  of  thickness.  Now  if  it  requires  a  leg  muscle  of 
eight  cm.  for  safety,  as  a  matter  of  fact  almost  all  the  indi- 
viduals of  the  species  will  quickly  bring  their  leg  muscles  up 
to  that  size  by  use.  But  suppose  the  actual  need  for  safety 
was  a  leg  muscle  of  fourteen  cm.,  then  only  those  individuals 
specially  capable  of  that  ontogenetic  adaptation,  i.  e.  (modi- 
fication of  the  leg  muscle  by  use  and  trophic  irritability),  up 
to  fourteen  cm.,  would  be  saved;  and  undoubtedly  among 
these  the  original  eight  cm.  individuals  ought  to  stand  in 
slightly  higher  numerical  proportion  (in  regard  to  their 
original  numerical  standing  in  the  species)  than  the  origi- 
nally seven  cm.  individuals.  Since,  however,  these  eight  cm. 
individuals  originally  existed  only  in  comparatively  small 
number,  and  since  they  possess  no  special  means  of  recognis- 
ing each  other  and  distinguishing  each  other  from  the 
original  seven  cm.  individuals,  mixed  mating  will  inevitably 
soon  swamp  the  original  congenital  increase  of  one  cm.  in 
muscle  thickness. 

In  connection  with  the  explanation  of  this  theory  it  will 
certainly  occur  to  some  of  my  readers,  as  it  has  to  me,  to  ask 
Danger  of  ^  ^  ^s  not  a  dangerous  proposal  to  give  to 
assuming  too  ontogenetic  adaptations  a  greater  worth  in 
Scfof^nto-"  deciding  the  fate  of  individuals  during  the 
genetic  selection,  struggle  for  existence  than  the  congenital  varia- 
tions. Is  this  not  proposing  to  take  away  from  the  fluctuat- 
ing, individiual,  so-called  Darwinian  variations  practically 
all  worth  and  capacity  except  as  they  are  of  immediate  use 
to  the  just-born  individuals,  i.  e.,  before  the  ontogenetic 
adaptations  have  been  able  to  develop  ?  Indeed,  why  is  it  not 
a  perfectly  legitimate  and  a  serious  criticism  of  congenital 
fluctuating  variations  that  they  must  be  overshadowed,  hid- 
den, and  overwhelmed  by  the  quick  and  large  ontogenetic 
or  individual  modification  of  which  practically  all  organisms 
are  capable  ?  Why  will  not  those  individuals  born  with  the 


212  DARWINISM   TO-DAY. 

better  and  larger  capacity  to  adapt  themselves  during  their 
ontogeny  to  their  needs  win  in  the  struggle  for  existence 
rather  than  those  born  with  predetermined  slightly  larger 
leg,  slightly  stronger  muscle,  etc.?  What  is  needed  is 
capacity  to  develop  by  use  and  functional  stimulus  a  much 
stronger  muscle,  a  much  swifter  flight  than  the  average. 
Those  individuals  that  are  capable  of  such  considerable  and 
really  worth  while  ontogenetic  adaptation  will  win  in  the 
struggle  for  existence;  and  while  they  may  not  hand  down 
by  inheritance  their  actually  acquired  characters,  will  they 
not  hand  down  their  inherited  congenital  capacity  for  con- 
siderable and  effective  ontogenetic  adaptation? 


APPENDIX. 

1  For  a   fairly  complete  bibliography,   with   abstracts,   of  all   the 
important   discussions   of   species-forming  theories   published   since 
1895,  see  L'Annee  Biologique   (ed.  Y.  Delage).     For  bibliography 
and  abstracts,  also  see  Zoologischer  Jahresbericht,  issued  annually 
by  the  Naples  Zoological  Station.     See  also  discussions  and  notes 
in  various  biological  journals,  as  Biologisches  Centralblatt,  Natural 
Science  (now  discontinued),  Nature,  Science,  American  Naturalist, 
etc. 

2  For  a  careful  account  and  discussion  of  Weismann's  work  and 
theories  as  far  as  developed  up  to  1893,  see  Romanes,  ''An  Exami- 

ListofWeia-  nation  of  Weismannism,"  1893.  Weismann's  pres- 
mann'a  evolution  ent-day  position  and  his  arguments  for  the  selection 
PaPers>  theories  are  set  out  in  his  "Vortrage  iiber  die  De- 

scendenztheorie,"  2  vols.,  1902,  which  we  may  look  on  as  consti- 
tuting a  manual  of  neo-Darwinism,  treating  all  the  more  familiar 
bionomic  phenomena  and  conditions  as  explained  by  selection. 
The  following  is  a  chronological  list  of  the  more  important  of 
Weismann's  publications : 

"t)ber  die  Berechtigung  der  Darwin'schen  Theorie,"  1868. 

"Uber  den  Einfluss  der  Isolirung  auf  die  Artbildung,"  1872. 

"Studien  zur  Descendenztheorie :  I,  Uber  den  Saison-Dimorphis- 
mus  der  Schmetterlinge,"  1875. 

"Uber  die  Dauer  des  Lebens,"  1882. 

"Uber  die  Vererbung,"  1883. 


OTHER   THEORIES   OF   SPECIES-FORMING.        213 

"Uber  Leben  und  Tod,"    1884. 

"Die  Continuitat  des  Keimplasmas  als  Grundlage  einer  Theorie 
der  Vererbung,"  1885. 

"liber  den  Riickschritt  in  der  Natur,"  1886. 

"Uber  die  Bedeutung  der  Sexuellen  Fortpflanzung  fiir  die  Selec- 
tionstheorie,"  1887. 

"Uber  die  Zahl  der  Richtungskorper  und  iiber  ihre  Bedeutung 
fiir  die  Vererbung,"  1887. 

"Botanische  Beweise  fiir  eine  Vererbung  erworbener  Eigenschaf- 
ten,"  1888. 

"Uber  die  Hypothese  einer  Vererbung  von  Verletzungen,"  1889. 

"Bemerkungen  zu  einigen  Tages  Probleme,"  1890. 

"Gedanken  iiber  Musik  bei  Tieren  und  beim  Menschen,"  1890. 

"Aufsatze  iiber  Vererbung  und  verwandte  Biologic,"  1892.  (This 
includes  the  eleven  preceding  papers  now  published  in  book- 
form.  These  essays  have  also  been  translated  into  French, 
by  H.  de  Varigny,  and  published  under  the  title:  "Essais  sur 
1'Heredite  et  la  Selection  Naturelle,"  1892;  and  also  in  Eng- 
lish as  "Essays  upon  Heredity  and  Kindred  Biological  Prob- 
lems," trans,  and  ed.  by  Poulton,  Shoneland,  and  Shipley,  2 
vols.,  1891  and  1893. 

"Amphimixis  oder  die  Vermischung  der  Individuen,"  1891. 

"Das  Keimplasma;  eine  Theorie  der  Vererbung,"  1892;  Eng. 
trans.,  by  Parker  and  Ronnfeldt,  as  "The  Germ-plasm;  a 
Theory  of  Heredity,"  1893. 

"Die  Allmacht  der  Naturziichtung,  eine  Erwiderung  an  H.  Spen- 
cer," 1893 ;  also  in  English  as  "The  All-sufficiency  of  Natural 
Selection,"  in  the  Contemp.  Review,  Vol.  LXIV,-  pp.  309-338, 
596-610,  1893. 

"The  Effects  of  External  Influences  upon  Development,"  Romanes 
Lectures,  1894 ;  also  in  German  as  "Aussere  Einfliisse  als 
Entwicklungsreize,"  1894. 

"Neue  Gedanken  zur  Vererbungsfrage,"  1894. 

"Uber  Germinal-Selection,"  in  Compt.  Rendus,  3d  Congress  In- 
ternat.  Zool.,  1896;  also,  in  English,  trans,  and  ed.  by  Mc- 
Cormack,  as  "On  Germinal  Selection  as  a  Source  of  Definite 
Variation,"  1896. 

"Thatsachen  u.  Auslegungen  in  Bezug  auf  Regeneration,"  Anat. 
Anzeig.,  Vol.  XV,  1899. 

"Vortrage  iiber  Descendenztheorie,"  2  vols.,  1902;  also  in  Eng., 
trans,  by .  J.  A.  Thomson  as  "Lectures  on  the  Theory  of 
Descent."  2  vols.,  1904. 

8  For  a  detailed  critical  discussion  of  panmixia,  see  Wolff,  "Der 
gegenwartige  Stand  des  Darwinismus,"  1896. 


214  DARWINISM   TO-DAY. 

4  Various  theories  of  ultimate  protoplasmic  structure  have  been 
proposed  to  explain  what  is  not  really  known  about  this  substance. 
Theories  of  ul-  These  theories  refer  almost  exclusively  to  the  physi- 
timate  protoplas-  cal,  rather  than  the  chemical,  make-up  of  protoplasm, 
mic  structure,  and  for  the  most  part  have  been  proposed  with 
special  attention  to  the  germ-plasm,  f.  e.,  the  protoplasm  of  the  sperm- 
and  egg-cells.  The  spur  to  the  formation  of  these  theories  is  the 
necessity  that  biologists  have  felt  imposed  on  them  from  the  be- 
ginning of  the  study  of  heredity  and  development  of  offering  some 
rational  explanation  of  those  phenomena.  That  from  a  single  germ- 
cell  formed  by  the  fusion  of  a  sperm-cell  and  an  egg-cell  from 
different  parents,  a  complete  new  organism  composed  of  millions 
of  cells  of  manifold  variety  of  specialisation  and  arrangement  can 
develop,  is  wonder  enough ;  but  that  this  new  organism  shall  repeat 
in  all  its  parts  with  extraordinary  fidelity  the  structure  and  physi- 
cal idiosyncrasies  of  one,  or  show  a  combination  of  the  character- 
istics of  both,  of  the  individuals  from  which  came  the  original 
single  sperm-  and  single  egg-cell,  adds  wonder  to  wonder.  What 
physical  or  structural  basis  is  there  in  the  fertilised  egg-cell  that  it 
can  represent  in  its  tiny  self  the  whole  of  a  giant  body,  like  that  of 
an  elephant,  whose  every  detail  it  can,  by  a  process  of  development 
under  suitable  extrinsic  conditions  of  temperature,  food-supply,  etc., 
repeat  in  a  new  creature.  The  answers  to  this,  all  purely  specula- 
tive, or  more  fairly  theoretical,  because  some  of  the  answers  at 
least  have  been  guarded  in  their  forming  by  all  the  care  which  a 
rigorous  scientific  attitude  toward  hypothesis  demands,  are  many 
and  various,  and  date  from  the  days  of  the  Greek  philosophers  to 
the  present  hour.  It  would  take  too  much  space  and  carry  us  too 
far  afield  to  attempt  anything  like  an  explanatory  list  of  even  all 
of  the  better  known  of  these  general  theories  of  the  invisible  ulti- 
mate structure  of  the  germ-plasm  here,  but  by  selecting  seven  or 
eight  types  of  the  principal  categories  or  kinds  of  these  theories, 
and  briefly  explaining  them,  we  may  have  at  least  some  conception 
of  the  attitude  that  biologists  take  toward  this  great  problem.  The 
reader  who  has  a  fancy  for  following  this  subject  further  is  re- 
ferred to  the  admirably  full  and  lucid  treatment  of  it  in  Delage's 
great  work,  "UHeredite"  (2d  ed.,  pp.  431-772,  1903). 

Most  of  these  theories  include  much  more  in  them  than  a  simple 
speculation  as  to  the  ultimate  structure  of  the  life-substance ;  they 
attempt  to  explain  all  the  phenomena  of  life,  motion,  nutrition, 
growth,  reproduction,  development,  heredity,  variation,  etc.,  with 
reference  to  some  assumed  ultimate  make-up  of  the  primitive  life- 
substance,  and  the  relation  of  this  structure  to  the  known  physico- 
chemical  forces  and  conditions  of  Nature.  Most  of  the  older 


OTHER   THEORIES   OF   SPECIES-FORMING.        215 

theories  assumed  a  peculiar  vital  force,  which  is  not  assumed  in 
the  later  ones,  although  exception  must  be  made  to  this  statement  in 
favour  of  the  point  of  view  held  by  the  recent  so-called  neo-Vitalists, 
those  present-day  workers  who  admit  the  hopelessness  of  trying  to 
reduce  all  vital  phenomena  to  a  physico-chemical  basis. 

An  old  type  of  theory  of  heredity  and  structure  of  the  germ- 
plasm,  widely  held  in  the  seventeenth  and  eighteenth  centuries,  is 

Encasement       that  of  the  "encasement  of  the  germ"  in  one  of  the 
theory,  germ-cells,  either  the  spermatozoid  or  the  egg.     The 

essential  part  of  this  theory  is  that  the  new  organism  is  assumed 
actually  to  exist  in  miniature,  with  all  its  parts  present,  in  one  of  the 
.germ-cells,  and  in  this  miniature  body  must  exist,  by  repeated  encase- 
ment, all  its  future  progeny.  Whether  the  believer  in  this  theory  con- 
sidered the  tiny  new  creature,  only  needing  to  swell  and  grow  to  be 
complete,  to  be  encased  in  the  sperm-cell  or  the  egg-cell,  ranked 
him  respectively  with  the  spermatists  or  the  ovalists.  A  vigorous 
strife  raged  between  these  two  factions  among  the  upholders  of 
this  simple  and  effective  explanation  of  heredity  which  led  to  cer- 
tain interesting  compromises.  A  commonly  held  one  was  that  the 
sperm-cell  furnished  the  spiritual  element,  the  egg-cell  the  material 
and  mechanical  elements  of  the  new  creature.  Another,  held  by 
Linnaeus,  the  great  botanist  and  father  of  biological  classification, 
was  that,  in  plants,  the  egg  (ovule)  furnished  the  internal  and  re- 
productive organs,  while  the  sperm-cell  (pollen)  furnished  the  exter- 
nal and  vegetative  parts.  De  Candolle,  another  great  botanist,  held 
just  the  reverse  of  this  view.  All  these  theories  of  an  actual 
•encasement  in  the  germ-cells  of  a  whole  or  part  of  a  new  organism 
were  not  mere  guesses,  but  were  based  on  what  men  thought  they 
saw  through  their  microscopes.  The  long  reign  of  these  theories, 
now  shown  to  be  utterly  absurd,  illustrates  well  the  constant  dan- 
ger which  attends  our  attempts  in  all  biological  study  to  interpret 
what  we  see  when  working  at  the  limits  of  visibility.  With  our 
much-improved  microscopes  we  laugh  at  the  fantasies  which  the 
microscopic  vision  of  our  eighteenth-century  co-workers  raised  up. 
Who  may  say  that  our  own  interpretations  of  plasm-structure  may 
not  seem  as  absurd  to  the  biologists  of  the  next  century? 

By  far  the  great  majority  of  theories  of  ultimate  protoplasmic 
structure  belong  to  what  Delage  calls  the  category  of  theories  of 

Micromeric        micromerism.      Which    means    simply   that    all    these 
theories.  theories   assume   a   composition  of  the  plasm   out   of 

minute  ultra-microscopic  units  of  structure,  which  are  also  units 
of  life,  for  all  these  units  are  presumed  to  be  endowed  with  the 
essential  life-attributes.  These  units  may  be  looked  on,  as  they 
were  by  Buffon,  as  universal,  indestructible,  hence  immortal,  parti- 


216  DARWINISM   TO-DAY. 

cles,  or,  as  they  are  in  most  of  the  micromeric  theories,  as  living 
particles  which  are  destroyed  with  the  death  of  the  organism 
which  they  compose.  In  this  latter  type  of  assumption  the  units 
are,  according  to  some  theories,  all  of  the  same  nature,  all  exer- 
cising an  equal  influence  in  determining  the  character  of  a  devel- 
oping organism  (Spencer,  Haacke,  His,  Cope)  ;  or  they  are,  as 
assumed  in  other  theories,  of  various  character  and  charged  with 
various  functions.  This  latter  kind  of  unit  is  held  by  some  authors 
to  be  actually  representative  either  of  ancestral  plasmas  (Weismann) 
or  of  the  actual  body-cells  of  the  parent  (Darwin,  Galton,  Brooks, 
Hallez),  or  of  elementary  characteristics  and  functions  of  the 
organism  (Nageli,  Kolliker,  de  Vries,  O.  Hertwig),  or  at  the  same 
time  of  both  body-parts  and  elementary  characteristics  (Weismann's. 
latest  theory). 

Buffon's  theory  assumed  that  "the  substance  of  which  organisms 
are  composed  differs  essentially  from  that  which  composes  the 
Buffon's  inorganic  bodies.  Organisms  are  composed  of  special 

theory.  particles,  the  organic  molecules.  These  molecules  are 

universal  and  indestructible:  universal  in  that  they  exist  everywhere 
where  life  has  access,  indestructible  in  that  death  and  the  dissolution 
which  follows  destroy  the  organisms,  break  down  the  molecular  com- 
binations which  constitute  them,  but  do  not  reach  the  molecules 
themselves.  These  are  only  separated,  put  at  liberty,  but  remain 
ready  to  enter  into  new  groupings.  While  they  cannot  be  de- 
stroyed, neither  do  they  increase  in  numbers.  They  form  nothing 
actually  new,  either  spontaneously,  or  by  means  of  old  ones,  so- 
that,  measured  by  these  organic  molecules,  the  total  quantity  of  life 
in  the  universe  is  invariable"  (Delage).  Nearly  a  hundred  years 
later  Bechamp  (1883)  proposed  a  theory  similar  to  Buffon's  in 
which  he  assumed  the  composition  of  organisms  out  of  minute 
elementary  living  particles  called  microsymes.  Like  Buffon's 
organic  molecules  they  are  indestructible,  and  they  are  strewed  in 
innumerable  numbers  through  earth,  air,  and  water.  They  owe  their 
origin  to  special  creation  by  God. 

Of  the  non-immortal  kind  of  micromeres  Spencer's  physiological 
units  represent  a  general  type  favoured  by  numerous  theorists  L 
namely,  living  units  all  of  the  same  nature  and  active  because  of 
their  polarity,  their  form  and  molecular  forces,  or  their  vibratory 
motion.  Spencer's  physiological  units  are  active  because  of  their 
polarity,  but  the  annular  atoms  of  Dolbear's  theory  and  the 
plastidules  of  the  slightly  varying  theories  of  Haeckel,  His,  Cope, 
and  others,  owe  their  active  properties  to  their  vibratory  motion. 

According  to  Spencer  (1864),  there  exist  between  the  cells 
(morphological  life-units)  and  the  molecules  which  compose  them 


OTHER   THEORIES   OF   SPECIES-FORMING.        217 

(chemical  units),  units  of  a  third  order  (physiological  units)  com- 
Bpencer's          posed  of  groups  of  molecules.     These  units  are  very 
theory.  small  but  very  complex,  and  are  the  smallest  masses  in 

which  living  substance  can  occur.  Most  of  the  micromeric  theories, 
which  come  after  Spencer's,  adopt  this  conception  of  a  life-unit,  very 
small,  but  composed  of  an  aggregate  of  molecules,  and  therefore 
very  complex.  To  his  physiological  units  Spencer  attributed  a 
polarity,  wholly  analogous  with  that  possessed  by  the  molecules 
of  crystalline  substances.  It  is  owing  to  this  delicate,  precise 
polarity,  varying  of  course  with  the  varying  molecular  consti- 
tution of  the  units,  that  they  possess  the  capacity  of  actively 
arranging  themselves  in  the  varied  groupings  normal  to  the  parts 
of  the  organisms.  "Thus  the  resemblance  is  perfect  between  the 
chemical  polarity  which  causes  crystallisation  and  that  of  the 
physiological  units  which  produces  the  form  of  organisms.  In  one 
case  the  chemical  molecules  group  themselves  in  a  manner  to  form 
an  aggregate  of  definite  but  simple  form,  cubical,  prismatic, 
rhomboidal,  with  their  parts  arranged  en  tremies,. aiguilles,  croix 
de  Saint  Andre,  boules  epineuses,  etc.  In  the  other  the  units  group 
themselves  in  a  body  of  a  form  less  rigorously  defined  but  which 
may  be  very  complicated:  such  as  a  plant  or  an  animal."  (Delage.) 

Of  the  theories  in  which  the  living  units  are  assumed  to  be  of 
different  kinds,  and  endowed  with  different  functions,  some  assume 
the  units  to  be  not  directly  representative  of  different  cells  or  parts 
of  the  body,  while  others  assume  this  truly  representative  condition. 
Of  the  first  sort  are  a  number  of  theories  like  those  of  Berthold, 
Geddes,  and  others,  in  which  the  units  are  taken  to  be  actual 
chemical  molecules,  endowed  with  activity  through  special  physico- 
chemical  properties  or  through  purely  chemical  ones,  while  still 
others  keep  to  the  more  usual  type  of  a  unit  of  a  higher  order 
than  a  molecule,  in  which  case  also  this  unit  is  looked  on  as  spe- 
cially active  because  of  particular  electrical  (Fol)  or  chemical 
(Altmann  and  Maggi)  or  vital  (Wiesner)  endowment.  But  all  of 
these  theories  are  much  like  each  other  and  are  much  like  Spencer's 
theory  in  regard  at  least  to  the  assumed  units.  Different,  how- 
ever, is  the  type  of  theory  which  introduces  the  assumption  that 
the  fundamental  life-units  are  directly  representative  of  either 
the  specific  cells,  parts,  or  elementary  characteristics  of  the  organ- 
ism. This  is  the  kind  of  unit  especially  favoured  by  the  men 
who  had,  in  their  formation  of  a  theory,  a  special  eye  to  the 
problem  of  heredity.  How  is  the  single  germ-cell  to  be  the  bearer 
of  the  "heredity"  of  the  organism  from  which  it  comes?  what 
more  simple  to  assume  than -that  this  cell  shall  be  composed  of 
minute  particles  gathered  from  all  the  cells  or  groups  of  similar 


DARWINISM   TO-DAY. 

•cells  of  the  body  of  the  parent  ?  And  that  is  precisely  the  charac- 
teristic assumption,  dressed  up  in  an  ingenious  variety  of  form, 
which  charac.erises  the  theories  of  life-units  most  favoured  at 
present:  such  theories  are  those  of  Darwin,  Galton,  Brooks,  Nageli, 
de  Vries,  Hertwig,  and  Weismann.  In  some  of  these,  interesting 
attempts  are  introduced  to  connect  the  assumed  structure  with 
the  actually  observed  finer  structure  of  the  nuclear  protoplasm,  by 
introducing  combinations  of  the  fundamental  units,  in  one  or  two, 
or  even  three,  successive  degrees  until  an  aggregation  is  reached 
which  corresponds  with  those  microscopic  structures,  the  chromo- 
somes, or  chromatin  granules  or  threads,  which  are  actually  visible 
to  the  microscope-aided  eye.  The  most  recent  one  of  the  theories 
of  this  general  type  is  that  of  Weismann's  biophors  and  determi- 
nants structure  of  the  germ-plasm,  already  explained  in  connection 
with  the  presentation  of  his  theory  of  germinal  selection  (see  pp. 
193  ff.).  As  other  examples  we  may  note  especially  Darwin's, 
called  the  theory  of  the  pangenesis  of  gemmules;  and  Nageli's, 
called  the  theory  of  micellae  and  idioplasm. 

Darwin's  gemmules  are  extremely  minute  particles,  which  are 
formed  in  all  the  various  cells  of  the  body  and  are  capable  of  repro- 

Darwin's  ducing  themselves  rapidly  and  in  great  numbers  by 

theory,  repeated  division,  and  which,  by  virtue  of  their  minute 

size  and  an  innate  activity  due  to  a  sort  of  affinity  or  attraction  exist- 
ing between  them  and  other  substances,  move  about  freely  in  the  body, 
penetrating  any  membranes,  and  arranging  themselves  with  a  deli- 
cate precision  just  where  they  are  most  needed.  When  a  gemmule 
enters  an  undifferentiated  or  developing  cell  as  yet  containing  no 
other  gemmules,  it  controls  the  development  of  that  cell  so  that  it 
becomes  a  cell  of  the  type  from  which  the  gemmule  had  birth,  each 
gemmule  representing  thus  exactly  the  characteristics  and  the  type 
•of  its  mother  cell.  Thanks  to  the  delicate  and  precise  adjustment 
of  affinities,  migrating  gemmules  only  enter  those  cells  which  they 
really  should  enter  in  order  that  a  normal  development  of  all  the 
cells  of  the  body  should  go  on.  But  those  few  cells  of  the  body 
which  are  destined  to  become  germ-cells,  that  is  the  spermatozoids 
and  eggs  in  animals,  the  pollen  grains  and  ovules  in  plants,  receive 
during  their  formation  gemmules  from  all  the  other  cells  of  the 
body.  Not  only  from  all  the  cells  of  the  fully  developed  body,  but 
from  all  those  ephemeral  cells  which  arise  and  live  for  a  while 
during  the  ontogeny  of  the  parent,  performing  certain  special  func- 
tions and  then  making  way  for  the  definitive  cells  of  the  mature 
organism.  Thus  in  the  germ-cells  are  stored  actual  physical  repre- 
sentatives of  all  the  cells  which  have  existed  during  the  whole  life 
of  the  parent  body.  These  innumerable  gemmules  remain  inactive 


OTHER   THEORIES   OF   SPECIES-FORMING.        219 

in  the  germ-cells  until,  after  fertilisation,  the  egg-cell  begins  its 
development.  Then  as  the  cells  of  the  new  organism  begin  to  be 
produced,  the  gemmules  become  active  and  each  one  moves  into 
the  cell  it  should  control  and  there  directs  its  further  development 
into  precisely  the  kind  of  cell  it  should  be  at  precisely  the  time  it 
.should  be  this  kind  of  cell,  until  there  results  from  this  gemmule- 
controlled  development  a  photographic  reproduction  of  the  parent 
"body. 

Nageli's  conception  is  that  when  the  complex  life-characterising  al- 
"buminous  substances  took  their  birth  in  an  aqueous  liquid,  they  would 

Nageli's  be  precipitated,  as  they  are  not  soluble  in  water.  This 

theory,  precipitate  is  formed  of  small  masses,  a  sort  of  organic 

crystals,  which  may  be  called  micella.  And  just  as  an  inorganic 
crystal  deposited  in  a  saturated  saline  solution  of  the  same  nature 
determines  the  deposit  on  its  surface  of  the  dissolved  molecules  in 
the  form  of  little  crystals,  and  by  this  means  grows,  so  wherever 
any  micellae  are  formed  they  facilitate  within  their  sphere  of  influ- 
ence the  precipitation  of  others,  so  that  this  production  of  micellae 
instead  of  taking  place  miscellaneously  through  the  liquid  will  be 
localised  at  certain  points.  Thus  arise  aggregates  of  albuminous 
substance,  in  the  condition  of  micellae,  forming  the  primitive 
protoplasm.  The  micellae,  although  insoluble  in  water,  have  a  great 
affinity  for  it,  and  each  one  at  the  time  of  its  precipitation  fixes 
around  itself  a  thin  layer  of  water,  at  least  as  thick  as  a  water 
molecule.  Thus,  all  the  micellae  grouped  together  in  a  bit  of  primi- 
tive protoplasm  are  separated  from  each  other,  and  also  held  to- 
gether by  a  layer  of  water  as  thick  as  two  water  molecules.  This 
water  forms  an  integral  part  of  the  protoplasm.  By  virtue  of  it,  an 
aggregate  of  albuminous  micellae  can  increase  by  intercalcation  as 
well  as  by  the  addition  of  new  micellae  on  the  outer  surface.  By 
admitting  more  or  less  water  the  protoplasmic  mass  may  become 
more  or  less  nearly  fluid.  Thus  are  accounted  for  the  various 
densities  always  met  with  in  the  different  parts  of  a  protoplasmic 
-cell. 

A  further  essential  part  of  Nageli's  theory  is  an  arrangement  of 
the  primitive  protoplasm  in  two  ways,  resulting  in  two  kinds  of  it, 
which  are  called  nutritive  plasm  and  idioplasm  respectively.  This 
arrangement  depends  on  the  molecular  forces  pertaining  to  the 
micellae,  and  the  difference,  resulting  in  two  kinds  of  plasm,  depends 
upon  the  relative  situation  of  the  micellae  composing  the  mass,  just 
Tiow  this  affects  them  differently,  however,  not  being  made  very  clear. 
But  the  differentiation  is  very  important,  for  it  is  the  idioplasm 
alone  which  contains  the  essential  life-properties  and  which  really 
gives  rise  to  life  with  all  its  variety  and  complexity.  This  idioplasm 


220  DARWINISM   TO-DAY. 

is  formed  at  first  in  scattered  bits  in  the  nutritive  plasm  mass,  but 
as  these  bits  increase  they  join  and  become  united  into  a  network 
surrounded  by  and  containing  in  its  meshes  the  nutritive  plasm. 
And  one  of  the  most  interesting  parts  of  Nageli's  hypothesis  is  that 
he  conceives  this  network  of  idioplasm  not  to  be  limited  by  cell 
boundaries  but  to  penetrate  from  one  cell  into  adjacent  cells  and 
thus  to  spread  through  and  unite  in  a  most  significant  and  important 
way  all  the  cells  and  tissues  of  the  body.  It  is  just  this  sort 
of  a  ramifying,  stimulus-carrying,  protoplasmic  network  connect- 
ing all  the  parts  of  the  body  that  the  believers  in  the  inheritance 
of  acquired  characters  seem  to  need  as  a  mechanism  to  transmit 
from  soma  to  germ-cells  the  effects  of  external  and  functional 
stimuli. 

Next,  the  theory  of  intra-cellular  pangenesis  of  de  Vries  may 
be  briefly  stated.  This  theory  has  become  the  more  important  be- 
cause of  the  great  interest  aroused  by  and  the  large  appreciation 
given  to  the  mutations  theory  of  species-forming  of  the  same 
biologist.  De  Vries's  theory  of  intra-cellular  pangenesis  has  much 
in  common  with  Darwin's  theory  of  the  pangenesis  of  gemmules, 
but  it  is  able  to  do  away  with  that  particularly  weak  part  of  Dar- 
win's theory,  which  postulated  the  circulation  of  the  gemmules 
throughout  the  organism  in  order  that  the^^hould  meet  in  the 
germ-cells  and  modify  these  cells  in  a  paraH^^^y  with  the  modi- 
fications occurring  in  the  peripheral  organs.  ^IBn  nad  to  postu- 
late this  circulation  of  the  gemmules  through  the^fcganism  in  order 
to  explain  the  phenomena  of  regeneration,  and  fhe  heredity  of 
acquired  characters.  Now  that  the  heredity  of  acquireVcharacters 
has  been  shown  to  be  at  best  an  extremely  doubtful  phenomenon, 
and  that  regeneration  is  explicable  by  other  means,  de  Vries  has 
been  able  to  drop  this  weakest  part  of  the  Darwinian  conception. 
So  that  in  the  theory  of  the  later  biologist,  the  circulation  of  gem- 
mules  does  not  extend  from  one  cell  to  another  throughout  the 
body  of  the  organism,  but  limits  itself  to  that  particular  cell  in 
which  it  is  created  and  circulates  only  between  the  nucleus  and 
cytoplasm,  from  which  comes  the  name,  "intra-cellular  pangenesis," 
as  distinguished  from  Darwinian  pangenesis.  De  Vries'  theory  may 
be  abstracted  as  follows  (following  Delage)  : 

The  form  and  properties  of  cells  result  from  their  protoplasmic 
composition  just  as  the  properties  of  the  inorganic  bodies  result 
De  Vries's  from  their  chemical  composition.  Is  it  necessary,  then, 
theory,  to  admit  that  there  are  as  many  kinds  of  protoplasm  as 

there  are  different  sorts  of  cells  in  the  organised  beings?  When  one 
recalls  how  many  different  cells  there  are  in  a  single  organism,  and 
that  the  homologous  cells  are  not  identical  in  different  species,  one 


OTHER   THEORIES   OF   SPECIES-FORMING.        221 

realises  the  incalculable  number  of  these  cells  and  despite  the  rich- 
ness in  variety  of  proteid  substances,  it  will  be  impossible  to  con- 
ceive that  each  kind  of  cell  should  have  its  own  kind  of  proto- 
plasm. There  is  here,  apparently,  an  insurmountable  difficulty,  but 
one  which  it  is  easy  to  do  away  with  by  a  very  simple  concep- 
tion. This  conception  consists  in  distributing  the  complex  charac- 
ters and  properties,  innumerable  in  living  beings,  into  elementary 
characters  and  properties  much  less  numerous,  which,  by  varying 
combinations,  produce  the  almost  infinite  variety  that  we  observe 
in  the  inorganic  world.  Just  as  with  a  score  and  a  half  of  letters 
one  may  form  all  of  the  words  of  the  human  language,  so  with  the 
elementary  properties  of  which  the  actual  number  is  still  very  con- 
siderable, one  may  reproduce  all  the  characters  of  living  beings  in 
all  their  variety  and  complexity.  It  suffices,  then,  to  admit  that 
these  elementary  characters  and  properties  are  represented  by  as 
many  material  particles,  and  the  problem  is  solved.  These  particles 
are  the  pangenes. 

The  pangenes,  then,  are  small,  organic  particles,  invisible  to 
the  microscope,  formed  of  an  enormous  number  of  chemical  mole- 
cules and  differing  from  the  most  complex  chemical  substances 
by  three  properties  which  are  common  to  all  of  them  and  which 
are  characteristic  of  living  matter;  they  nourish  themselves,  in- 
crease in  size,  and  multiply  themselves  by  division.  Beside  these 
three  general  properties  which  make  living  molecules  of  them, 
the  pangenes  possess  particular  properties  depending  upon  their 
chemical  constitution,  differing  for  each  of  them,  and  which  are 
bound  to  them  indissolubly  in  such  a  manner  that,  wherever  a 
pangene  finds  itself,  the  elementary  property  or  character  special  to 
it  will  show  itself  if  internal  and  external  conditions  permit  of  this 
manifestation.  Latent  or  patent,  potentially  or  evidently,  the  char- 
acter is  always  there  where  is  the  corresponding  pangene.  Each 
cell  contains  a  great  number  of  pangenes  in  activity,  and  its  charac- 
ters and  properties  in  sum  are  the  resultant  of  the  elementary 
characters  and  properties  of  the  pangenes  composing  it:  just  as  the 
anatomical  and  physiological  characters  and  properties  of  the  living 
individual  are  resultant  of  the  anatomical  and  physiological  charac- 
ters of  the  cells  composing  it. 

It  is  necessary  to  conceive  of  the  cellular  protoplasm  as  formed 
of  innumerable  pangenes  bathed  in  a  liquid  in  which  are  dissolved 
substances  purely  chemical :  albumen,  glucose,  salts,  etc.  Perhaps 
similar  substances  penetrate  the  pangenes  themselves,  but  we  do 
not  know  this. 

The  nucleus  contains  in  general  all  the  kinds  of  pangenes  that 
compose  the  individual.  But  these  pangenes  are  there  in  a  sort 


222  DARWINISM   TO-DAY. 

of  inactivity,  in  reserve,  in  order  to  be  transmitted  to  the  daughter 
nucleus  when  the  cell  divides.  They  can  divide  themselves,  and  it 
is  indeed  necessary  that  this  be  so  in  order  that  the  two  daughter 
nuclei  can  each  receive  a  complete  lot  of  the  representative  pan- 
genes;  but  they  do  not  manifest  in  the  nucleus  their  special  proper- 
ties, which  remain  in  a  latent  state.  There  is  no  exception  to  this 
except  in  the  case  of  those  certain  pangenes  which  control  the 
division  of  the  nucleus.  These  enter  into  activity  at  the  necessary 
moment  in  order  to  determine  the  characters  of  the  division  and 
in  particular  the  position  of  the  plane  of  segmentation. 

The  cytoplasm  is  also  composed  of  pangenes ;  but  these  pangenes,. 
with  the  exception  of  those  which  come  from  the  cytoplasm  of  the 
egg.  come  from  the  nucleus.  From  the  nucleus  there  come,  in  fact, 
pangenes  which  distribute  themselves  in  the  cytoplasm  and  multiply 
there  abundantly.  These  pangenes  are  exclusively  those  of  which 
the  cytoplasm  has  need  in  order  to  manifest  characters  and  proper- 
ties which  belong  to  the  cell,  and  it  is  by  delivering  to  it  such  and 
such  pangenes  and  no  others  that  the  nucleus  rules  the  cytoplasm, 
which  would  remain  inert  were  it  not  for  this  infusion  of  living 
and  active  particles. 

There  is,  then,  a  great  difference  between  the  nucleus  and  the 
cytoplasm  from  the  point  of  view  of  the  pangenetic  constitution. 
Each  nucleus  contains  in  general  all  the  pangenes  of  the  individual 
united  undoubtedly  into  groups  more  or  less  considerable,  which  lie 
in  the  chromatic  filaments,  and  these  groups,  analogous  to  the 
gemmules  of  Darwin's  theory,  probably  form  those  little  grains 
arranged  in  rows,  which  are  revealed  under  a  great  microscopic 
magnification  of  the  chromatic  threads.  But  there  are  one,  two,  or, 
at  most,  a  small  number  of  pangenes  of  each  kind;  all  are  inactive 
save  at  the  moment  of  division,  those  which  rule  this  phenomenon; 
they  can  multiply  themselves  but  slightly,  and  in  general  they  do 
not  divide  except  to  replace  those  which  emigrate  into  the  cyto- 
plasm and  to  furnish  at  the  moment  of  division  to  each  daughter 
nucleus  the  complete  lot  which  it  ought  to  receive.  In  the  cyto- 
plasm, on  the  contrary,  there  is  but  a  small  number  of  kinds  of 
pangenes  immigrated  from  the  nucleus  in  the  quantity  exactly 
necessary,  but  there  these  pangenes  are  enormously  multiplying,  so 
that  there  is  a  very  great  number  of  each  kind,  and  they  are  almost 
always  in  a  state  of  activity. 

B.  Hatschek  has  recently  proposed  ("Hypothese  der  Organischen 

Vererbung,"  1905)   a  new  micromeric  theory  which  postulates  that 

Eatschek's         the  protoplasm  is  composed  of  two  different  kinds  of 

theory.  biomolecules ;  one  called  ergatules,  which  function  as- 

similatively,  that  is,  take  up  food-stuff  and  excrete  waste,  but  do  not 


OTHER   THEORIES   OF   SPECIES-FORMING.        223; 

possess  a  capacity  for  growth  or  self-reproduction;  second,  the  gen- 
eratules,  which  have  no  particular  functional  work  to  perform  but  can 
grow  and  reproduce  themselves  and  can  carry  over  this  capacity  of 
reproduction  to  the  ergatules,  because  they  can  fuse  with  them  or 
attach  themselves  to  them  and  thus  carry  over  to  them  their  char- 
acteristic peculiarities.  These  generatules  are  looked  on  as  the 
chemical  radical  of  the  ergatules,  and  become  therefore  the  directly 
determining  agents  for  all  peculiarities  of  the  body.  The  ergatules 
sit  chiefly  in  the  cytoplasm  of  the  cell,  while  the  generatules  lie  in  the 
cell  nucleus,  especially  in  the  chromosomes,  and  therefore  render 
these  the  bearers  of  hereditary  characteristics. 

Thus  baldly  and  wholly  incompletely  stated  these  theories  of 
ultimate  plasm  structure  which  shall  be  of  a  sort  to  agree  with  all 
the  varied  phenomena  of  life,  and  particularly  those  of  heredity, 
show,  unfortunately,  only  their  fantastic  face.  For  as  it  is  pre- 
cisely in  showing  how  the  postulated  structure  and  properties  are 
perfectly  consonant  with  all  the  known  phenomena  of  life  that 
these  theories  have  their  actual  interest  and  strength,  a  fantastic: 
and  improbable  face  shown  as  to  this  robs  them  of  all  interest.  But, 
perhaps,  it  is  well  that  the  fantastic  aspect  of  them  should  be  first 
recognised.  For  it  is  only  fair  to  say  that  the  ingenuity  and  plausi- 
bility, the  precise  and  exhaustive  development  of  detail,  of  some  of 
these  theories,  are  really  dangerous  to  the  layman  who  first  happens; 
to  read  a  full  and  well-stated  account  of  one  of  them  by  an  enthu- 
siastic upholder.  One's  eyes  become  closed  to  the  fact  that  all  the* 
structure  and  performance  that  seem  so  natural,  and  fit  in  so 
exactly  with  all  that  we  actually  know  of  the  phenomena  of  life, 
have  not  been  seen,  only  imagined.  One  needs  an  introduction  to 
these  theories  which  insists  above  all  on  their  wholly  hypothetical 
character.  Otherwise  one  is  surprisingly  readily  hypnotised  into 
accepting  one  or  the  other  of  them  as  a  statement  of  fact.  These 
general  theories  are  the  atomic  theories  of  biology  without  one- 
tenth  the  probability  of  truth  or  one-tenth  the  actual  acceptance 
in  science  that  the  atomic  theory  of  the  chemists  has.  And  even 
that  is  beginning  to  be  discarded  in  modern  chemistry.  These- 
theories  are,  as  Weismann  has  said,  the  outcome  of  the  fact  that 
"the  deeper  one  studies  into  the  phenomena  of  heredity,  the  more 
one  is  convinced  that  something  of  this  kind  of  a  condition  [of  a 
composition  of  the  fundamental  life  substance  out  of  ultra-micro- 
scopic units  bearing  a  certain  spatial  relation,  and  one  of  attractions 
and  repulsions  to  each  other]  must  really  exist:  for  it  is  impossible 
to  explain  the  observed  phenomena  in  any  other  way,  that  is,  by 
any  much  simpler  assumption."  But  on  the  other  hand  a  sufficient 
reason  against  accepting  any  one  of  these  highly  developed  theories. 


224  DARWINISM   TO-DAY. 

of  the  structure  and  functional  capacity  of  invisible  life-units,  is 
the  sagacious  one  of  Delage  when  he  says  that  simply  by  the  law 

Delage's  of  probabilities  it  will  be  impossible  by  pure  imagining 

criticisms,  to   explain  correctly  in   detail   the   ultimate   structure 

of  protoplasm.  Has  any  one,  asks  Delage,  guessed  in  advance,  with 
the  least  truth,  structures  which  the  microscope  has  later  been  able 
to  reveal  to  us  ?  Has  any  one  guessed  the  cross-striation  of  muscles, 
the  cilia  of  vibratile  epithelium,  the  prolongations  of  the  nerve- 
cells,  the  make-up  of  the  retina,  or  the  organ  of  Corti,  the  chromo- 
somes, the  centrosome?  Distinctly  not.  Delage  points  out  that 
the  chemists  had  a  much  better  chance  to  hit  the  truth  in  supposing 
atomic  structure,  for  they  had  a  much  less  complex  condition  to 
perceive,  and  they  had  approached  in  their  positive  knowledge  very 
much  nearer  the  hypothetical  element  which  they  adopted. 

Le  Dantec  criticises  the  micromeric  theories  of  protoplasmic 
structure  by  saying  that  all  these  theories  seek  to  make  mysteries 

Le  Dantec's  clearer,  complex  things  simpler,  by  reducing  large 
•criticisms,  things  to  small  ones.  A  man,  for  example  (he  says) 

is  composed  of  60  trillions  of  cells  and  is  nevertheless  produced  by 
sexual  elements  of  very  small  size ;  here  is  a  phenomenon  to  ex- 
plain. The  micromerist  says  that  the  difficulty  of  this  explanation 
would  be  less  (or  at  least  not  so  sharply  defined!)  if  one  divided 
the  problem  into  60  trillions  of  parts ;  that  is,  if  one  replaced  the 
reproduction  of  man  by  60  trillions  of  partial  reproduction.  One 
lias  therefore  imagined  particles  infinitely  small  which  are  to  the 
•cells  what  the  sexual  cells  are  to  the  man.  And  this  comparison  has 
been,  consciously  or  not,  claims  Le  Dantec,  the  point  of  departure 
of  all  the  systems  of  particulate  representation  in  the  germ- 
plasm. 

We  have  simply  substituted  for  a  single  heredity,  continues  the 
critic,  60  trillions  of  partial  heredities,  each  exactly  as  mysterious 
as  the  first.  Thus  these  60  trillions  of  gemmules  gathered  in  the 
egg  and  distributed  in  a  precise  manner  are  in  reality  only  a  dis- 
guising of  the  homunculus  of  the  ovalists.  Perhaps  we  have  no 
reason  to  suppose  that  these  gemmules  design  by  their  agglomeration 
this  invisible  homunculus,  but  at  least  it  is  certain  that  they 
are  disposed  in  a  manner  which  is  in  relation  to  the  form  of  the 
man  to  be  determined,  since  in  fact  each  of  them  represents  not 
alone  a  cell  of  the  man,  but  a  cell  with  the  place  it  is  to  occupy. 

One  sees  thus  how  complex  is  this  system  which  has  for  its  aim 
the  simplifying  of  the  question  of  heredity:  it  is  more  logical  to 
consider  simply  the  egg  as  having  the  power  to  produce  a  man  than 
to  attribute  a  power  as  mysterious  to  60  trillions  of  gemmules  to 
which  it  is  necessary  to  accord,  in  addition,  a  determinative  capacity 


OTHER   THEORIES   OF   SPECIES-FORMING.        225 

which  results  in  conducting  each  cell  to  exactly  that  place  which 
it  ought  to  occupy. 

In  addition  to  the  theories  of  an  ultimate  micromeric  structure 
of  protoplasm,  certain  other  recent  hypothetical  explanations  of 
Verworn's  bio-  the  special  properties  of  protoplasm  should  be  noted, 
gen  hypothesis,  One  is  the  biogen  hypothesis  of  Verworn,  the  physiol- 
ogist of  Gottingen,  one  the  chemism  theory  of  Le  Dantec,  one 
the  physical  machine  theory  of  Delage,  and  another  is  the  general 
vital  principle  hypothesis  of  the  neo-Vitalists.  Verworn's  hypoth- 
esis to  account  for  the  physiological  activities  of  protoplasm,  i.  e., 
the  special  life  attributes,  as  assimilation,  disassimilation,  growth, 
irritability,  etc.,  consists  in  the  postulation  of  a  complex  chemical 
compound  of  unknown  structure  called  biogen,  but  with  the  special 
capacities  of  an  enzyme.  This  biogen  is  assumed  to  be  constantly 
labile,  i.  e.,  breaking  down  and  rebuilding  itself  and  by  this  per- 
formance acting  as  a  go-between  (enzyme  or  perhaps  katalysator) 
between  the  atmospheric  oxygen  brought  to  the  cell  by  the  blood 
and  the  oxidisable  (food)  products  (also  brought  by  the  blood). 
Not  only  can  the  biogen  rebuild  itself,  but  by  polymerisation  it  can 
grow,  that  is,  increase  the  size  of  its  molecules  by  adding  side- 
chains  of  atoms.  This,  according  to  Verworn,  constitutes  cell 
growth.  This  growth  is  not  indefinite,  as  the  atoms  tend  to  break 
away  again  and  thus  there  is  a  limit  to  the  size  of  the  biogen  mole- 
cules. The  author  only  presents  his  conception  of  biogen  as  a  good 
working  hypothesis. 

Delage  has  also  offered  a  tentative  physico-chemical  explanation 
of  certain  of  the  properties  of  protoplasm,  as  its  movements,  its 
Delage's  ma-  nutrition,  and  even  its  reducing  division,  on  the  basis 
chine  theory.  of  osmotic  effects  due  to  the  constant  interchange  of 
substance  from  the  outer  layers  of  the  cell  protoplasm  to  the  inner 
through  fine  membranes  or  special  protoplasmic  layers  which  he 
assumes  to  enclose  each  cell  part,  i.  e.,  nucleus,  chromosomes,  etc. 
Nutrition,  for  example,  is  effected  according  to  Delage,  by  constant 
selective  osmotic  exchanges  between  the  liquid  and,  semi-liquid 
parts  of  the  cell,  the  blood-plasm  of  course  constantly  bringing 
food  and  carrying  off  excreta  to  and  from  the  periphery  of  each 
cell.  Cell  division  is  the  result  of  mutual  pulls  and  pushes,  its 
essential  feature  always  being  the  actual  sundering  of  parts;  but 
how  this  mechanical  process  is  guided  or  controlled  as  it  is,  or  even 
initiated,  is  left  unexplained. 

Le  Dantec  holds  that  life  is  a  chemical  phenomenon.     "La  vie  est 

Le  Dantec's  the-  un    phenomene    chimique,    c'est-a-dire    que    les    seuls 

ory  of  chemism.     caracteres    essentiels    par    lesquels    une    action    vitale 

differe  d'une  manifestation  de  1'activite  de  la  matiere  brute  sont  rela- 


226  DARWINISM   TO-DAY. 

tifs  a  des  destructions  et  des  constructions  d'edifices  moleculaires. 
Cette  verite,  toute  la  biologic  nous  la  prouvera  de  mille  manieres ;  il 
vaut  done  mieux  1'enoncer  en  commenc.ant,  de  maniere  a  ce  qu'elle 
prenne  la  premiere  place  dans  1'esprit  de  ceux  qui  se  livreront  a 
1'etude  des  etres  vivants. 

"Mais  une  reaction  chimique  n'est  pas  quelque  chose  d'isole  et 
ne  se  produit  que  dans  certaines  conditions  dont  la  realisation  peut 
etre  liee  a  des  particularites  d'ordre  physique  (chaleur,  electricite, 
lumiere,  etc.)  ;  de  plus,  elle  s'accompagne  tou jours  de  phenomenes 
accessoires  qui  sortent  egalement  du  domaine  de  la  chimie  (chaleur, 
mouvement,  etc.).  Ceci  est  vrai  surtout  pour  les  reactions  des 
matieres  vivantes,  a  cause  de  1'etat  tres  special  de  ce  qui  represente 
la  solution  de  ces  matieres  dans  1'eau.  La  vie  est  aquatique,  mais 
les  matieres  vivantes  ne  se  dissolvent  pas  comme  du  sel  marin" 
("Traite  de  Biologic,"  pp.  43-44,  1903). 

He  goes  on  to  discuss,  with  keen  analysis  and  ingenious  but  uncon- 
vincing synthesis,  the  various  primary  conditions  and  activities  of 
life,  explaining  each  vital  phenomenon  separately  on  a  basis  of 
chemism.  He  even  proposes  a  chemical  notion  of  species.  Such 
a  chemical  species  can  of  course  take  no  primary  account  of  form, 
but  as  conditions  of  chemical-  identity  will  usually  involve  identity 
of  form,  the  various  individuals  composing  a  chemical  species  will 
possess  a  similar  or  identical  form.  An  author,  undertaking  what 
Le  Dantec  undertakes,  must  necessarily  be  a  bold  thinker  and  a 
bold  writer.  The  present  author  is  both.  And  he  is  nowhere  unin- 
teresting or  unsuggestive,  but  also  is  he  nowhere  wholly  con- 
vincing. 

The  position  of  the  neo-Vitalists  is  perhaps  best  to  be  taken 
from  that  of  Driesch,  an  extremely  able  present-day  biologist,  whose 

first  belief  was  in  a  radical  mechanical  explanation  of 
Neo- Vitalism,      .,   ...  .    .„. 

all  life  phenomena,  and  whose  brilliant  experimental 

work  has  furnished  many  of  the  examples  referred  to  in  all  text-books 
of  the  modern  study  of  the  mechanics  of  development.  But  Driesch's 
present  position  is  an  uncompromising  belief  in  the  impossibility 
of  explaining  life-forms  and  life-functions  on  the  basis  of  ever  so 
complex  a  combination  of  purely  physico-chemical  and  mechanical 
conditions  and  factors.  Put  positively,  neo- Vitalism  demands  the 
assumption  of  an  extra-physico-chemical  factor  (called  "psychoid," 
according  to  Driesch's  nomenclature),  which  is  an  attribute 
of,  or  essential  kind  of  potentiality  pertaining  to,  organised 
living  substance,  and  not  found  in  nor  influencing  inorganic 
bodies. 

Biitschli  has  well  pointed  out  that  neo- Vitalism  is  really  only 
a  return  to  the  old  "vital  principle"  belief,  and  that  we  are  now, 


OTHER    THEORIES   OF   SPECIES-FORMING.        227 

and  have  been  ever  since  our  practical  giving  up  of  the  vital  prin- 
ciple notion,  making  steady  progress  in  the  explanation  of  life- 
forms  and  life-functions  on  strictly  mechanical  and  physico-chemical 
grounds.  While  we  have  by  no  means  explained  all  life  attributes 
in  this  way,  Biitschli  holds  that  our  progress  has  been  such  as  to 
make  no  demand  for  the  introduction  as  yet  of  a  new  vital  principle 
tinder  a  pseudo-scientific  guise. 

Other  neo-Vitalists,  of  whom  G.  Wolff  is  a  type,  lay  chief  stress 
on  the  inexplicableness  of  the  Zweckmassigkeit  in  organisms  by 
any  of  the  known  biological  facts  and  factors,  and  see  in  the  deter- 
mination or  very  existence  of  this  Zweckmassigkeit  the  chief  revela- 
tion of  a  vital  factor,  wholly  distinct  from  anything  found  in  the 
inorganic  world.  Wolff's  argument  is  clever  and  suggestive,  and 
brings  home  to  one  strongly  the  indissoluble  relationship  between 
living  matter  and  its  adaptivity.  In  its  fundamental  character  life 
is  adaptivity :  the  indispensable  relation  between  living  matter  and 
the  rest  of  nature  is  the  pliability,  the  adaptiveness  of  the  living 
matter.  "Die  sweckmassige  Anpassung  ist  das,  was  den  Organis- 
mus  sum  Organismus  macht,  was  sich  uns  als  das  eigentlichste 
Wesen  des  Lebendigen  darstellt.  Wir  konnen  uns  keinen  Organis- 
mus denken  ohne  dieses  Charakteristikum.  .  .  .  Und  wir  erkennen 
dass  jede  Erklarung,  welche  das  Leben  voraussetzt,  jede  postvi- 
tale  Erklarung  der  organischen  Zweckmassigkeit,  in  jedem 
Falle  voraussetzt  was  sie  erklaren  will;  wir  erkennen  dass  die 
Erklarung  der  Zweckmassigkeit  mit  der  Erklarung  des  Lebens 
zusammenf alien  muss" 

But  perhaps  there  is  a  difference  between  the  plastic  response  of 
protoplasm  to  the  varying  conditions  of  oxygen,  food,  temperature, 
etc.,  about  it,  so  that  within  certain  limits  of  external  versatility  it 
still  lives,  and  that  extraordinary  specialisation  of  fitness  which  we 
see  exhibited  by  a  parasitic  Sacculina  with  relation  to  its  crab 
host.  And  believers  in  natural  selection  hold  that  it  is  exactly  one 
of  the  chief  glories  of  selection  that  it  does  explain  this  highly 
specialised  fitness.  More  than  that,  closer  examination  of  the 
phenomena  of  organic  Nature  reveals  many  examples  of  an  unfit- 
ness,  which  certainly  ought  not  to  exist  if  there  is  a  special  vital 
principle  responsible  for  fitness  throughout  the  organic  kingdom. 
There  is  a  moth  common  with  us  here  in  California,  by  name 
Phryganidia  calif ornica,  whose  larvae  live  on  the  leaves  of  the  oak- 
trees.  Two  generations  appear  each  year.  The  eggs  for  the  first 
brood  of  caterpillars  are  laid  in  spring  by  the  moths  on  the  leaves 
of  the  live-oaks  and  also  of  the  white-oaks.  The  larvae  soon  hatch, 
feed  through  the  summer  on  the  leaves,  and  in  September  pupate, 
the  moths  appearing  in  October.  These  moths  now  proceed  to  lay 


228  DARWINISM   TO-DAY. 

the  eggs  for  the  second  generation,  which  eggs  are  also  deposited 
on  the  leaves  of  both  live-  and  white-oaks.  But  while  the  live-oak 
is  an  evergreen  tree,  the  white-oak  is  deciduous,  and  sheds  its 
leaves  soon  after  these  October  eggs  are  laid  on  them,  which  means 
that  one-half  of  this  second  generation  is  doomed  to  die  of  starva- 
tion immediately  after  hatching.  This  is  repeated  regularly  each 
year,  and  is  certainly  a  distinctly  unfit  habit  in  this  moth's  life 
economy.  Plate  refers  to  a  similar  instance  of  Unzweckmassigkeit 
as  follows:  "As  I  once  was  landing  on  Santa  Maria  Island  in  the 
Gulf  of  Aranco,  the  whole  shore  swarmed  with  thousands  of  giant 
cuttlefishes  (Ommatastrephes  gigas)  which  partly  lay  dead  on  the 
beach  and  partly  were  swimming  around  in  the  shallow  water. 
These  latter  instead  of  trying  to  get  back  into  deeper  water,  con- 
stantly swam  towards  the  land  until  a  breaker  threw  them  up  high 
and  dry.  Reflexes  and  instincts  often  make  mistakes,  that  is,  they 
result  in  actions  which  result  in  actual  harm,  and  nothing  is  more 
mistaken  than  the  declaration  that  an  organism  reacts  under  normal 
circumstances  always  in  a  way  to  serve  the  preservation  of  its  life. 
That  organisms  under  new  circumstances  or  in  abnormal  condi- 
tion very  often  react  unfitly,  requires  no  elaboration ;  every  light- 
house against  which  thousands  of  birds  and  insects  are  killed,  the 
toxicological  phenomena,  the  incomplete  regeneration,  every  club- 
foot,  and  every  Wasserkopf  prove  this.  The  countless  harmful  re- 
actions and  incompletenesses  in  structure  make  it  impossible  to 
speak,  in  the  vitalistic  sense,  of  an  inherent  Zweckmdssigkeit  of 
organisms,  of  a  tendency  always  to  change  in  the  direction  of  use- 
fulness. An  organism  is  exactly  as  definitely  ruled  by  chemico- 
physical  laws  as  every  dead  body.  Let  an  organism  happen  in  any 
set  of  conditions:  it  has  no  longer  the  choice  among  a  useful,  a 
harmful,  or  an  indifferent  reaction,  but  the  causal  chain  determines 
for  a  definite  direction  and  this  is,  as  a  thousandfold  observations 
show,  not  a  life-preserving  one,  in  other  words  is  not  zweckmassig. 
If  now  in  spite  of  this  organisms  have  become,  in  the  course  of 
earth-history,  even  more  complex  and  more  capable  and  have 
acquired  the  most  wonderful  adaptation,  there  must  obtain  some 
regulatory  principle  in  Nature,  which  we,  with  Darwin,  recognise 
as  actually  existing  in  the  struggle  for  existence  and  the  con- 
sequent selection  of  fit  variations.  If  organisms  actually  had  the 
capacity  to  direct  their  vital  activities  always  toward  the  side  of 
utility,  then  the  workings  of  the  natural  forces  would  be  over- 
come and  Mysticism  again  be  introduced  in  natural  philosophy. 
Both  actual  observation  and  the  theoretical  basis  of  natural  science 
give  no  basis  for  any  hypothesis  of  the  existence  in  organisms  of 
an  immanent  capacity  for  adaptive  reactions." 


OTHER   THEORIES    OF   SPECIES-FORMING.        229 

5  Weismann,  A.,  "On  Germinal  Selection  as  a  Source  of  Definite 
Variation,"  trans.  McCormack,  p.  3,  1896. 

8 1  quote  from  Morgan,  "Evolution  and  Adaptation,"  pp.  165-166, 
1903,  the  following  special  protest  against  the  means  of  escape  from 
M  n'  riti  a  ***&*•  P^ace  which  Weismann  has  taken  advantage  of 
cismofWeis-  in  his  dilemma:  "Thus  Weismann  has  piled  up  one 
mann's  method  hypothesis  on  another  as  though  he  could  save  the 
of  argument,  integrity  of  the  theory  of  natural  selection  by  adding 
new  speculative  matter  to  it.  The  most  unfortunate  feature  is  that 
the  new  speculation  is  skilfully  removed  from  the  field  of  verifica- 
tion, and  invisible  germs  whose  sole  functions  are  those  which 
Weismann's  imagination  bestows  on  them,  are  brought  forward 
as  though  they  could  supply  the  deficiencies  of  Darwin's  theory. 
This  is,  indeed,  the  old  method  of  the  philosophisers  of  nature.  An 
imaginary  system  has  been  invented  which  attempts  to  explain  all 
difficulties,  and  if  it  fails,  then  new  inventions  are  to  be  thought 
of.  Thus  we  see  where  the  theory  of  the  selection  of  fluctuating 
germs  has  led  one  of  the  most  widely  known  disciples  of  the  Dar- 
winian theory. 

"The  worst  feature  of  the  situation  is  not  so  much  that  Weismann 
has  advanced  new  hypotheses  unsupported  by  experimental  evi- 
dence, but  that  the  speculation  is  of  such  a  kind  that  it  is,  from  its 
very  nature,  unverifiable,  and  therefore  useless.  Weismann  is  mis- 
taken when  he  assumes  that  many  zoologists  object  to  his  methods 
because  they  are  largely  speculative.  The  real  reason  is  that  the 
speculation  is  so  often  of  a  kind  that  cannot  be  tested  by  observa- 
tion or  by  experiment." 

7  Roux,  W.,  "Der  Kampf  der  Theile  im  Organismus,"  1881. 

8  Baldwin,  J.  Mark,  "A  New  Factor  in  Evolution,"  Amer.  Nat., 
Vol.  XXX,  pp.  441  ff.,  1896;  see  also  the  .same  author's  "Develop- 

References  to  nient  and  Evolution,"  chap,  viii,  1902;  in  the  appen- 
discussions  of  dices  of  this  book  is  given  a  detailed  history  of  the 
orthoplasy.  independent  formulation  of  the  theory  of  "Organic 

Selection  or  Orthoplasy,"  by  Baldwin,  Osborn,  and  Morgan. 

9  Osborn,  H.  F.,  "A  Mode  of  Evolution  requiring  neither  Natural 
Selection  nor  the  Inheritance  of  Acquired  Characters,"  Trans.  New 
York  Acad.  Sci.,  pp.  141-148,  1896;  also  Science,  April  3,  1896;  also 
Amer.    Nat.,    Nov.,    1897.      From    this    last    reference    I    quote    the 
following  concise  statement  of  the  theory:   "This  hypothesis  as  it 
appears  to  myself  is,  briefly,  that  ontogenic  adaptation  is  of  a  very 
profound  character;   it  enables  animals  and  plants  to   survive  very 
critical  changes  in  their  environment.     Thus  all  the  individuals  of 
a  race  are  similarly  modified  over  such  long  periods  of  time  that, 
very  gradually,  congenital  variations  which  happen  to  coincide  with 


23°  DARWINISM   TO-DAY. 

the  ontogenic  adaptive  modifications  are  collected  and  become 
phylogenic.  Thus  there  would  result  an  apparent  but  not  real 
transmission  of  acquired  characters." 

10  Morgan,  C.  L.,  "Habit  and  Instinct,"  pp.  312  ff.,  1896;  see  also 
Science,  pp.  793  ff.,  Nov.,  1896.  In  Appendix  C  of  Baldwin's  "De- 
velopment and  Evolution,"  p.  347,  1902,  is  the  following  clear 
statement  (in  letter  to  Baldwin)  of  Morgan's  conception  of  organic 
selection : 

"i.  On  the  Lamarckian  hypothesis,  racial  progress  is  due  to  the 
inheritance  of  individually  acquired  modifications  of  bodily  struct- 
ure, leading  to  the  accommodation  of  the  organism  or  race  to  the 
conditions  of  its  existence. 

"2.  This  proposition  is  divisible  into  three:  (a)  Individual  prog- 
ress is  due  to  fresh  modifications  of  bodily  structure  in  accommo- 
dation to  the  conditions  of  life,  (b)  Racial  progress  is  due  to  the 
inheritance  of  such  newly  acquired  modifications,  (c)  The  evolu- 
tion of  species  is  the  result  of  the  cumulative  series — 

<'a>b+a'>b'+a">b"+a'">b'",  etc.,  etc.,  where  a.  a',  a",  a'"  are 
the  acquisitions,  and  b,  b',  b",  b'"  the  cumulative  inherited  results. 

"3.  Anti-Lamarckians  do  not  accept  (b)  and  (c).  But  they 
accept  (a)  in  terms  of  survival.  No  one  denies  that  individual 
survival  is  partially  due  to  fresh  modifications  of  bodily  structure 
in  accommodation  to  the  conditions  of  life. 

"4.  It  logically  follows  from  3  that  individual  accommodation  is  a 
factor  in  survival  which  cooperates  with  adaptation  through  ger- 
minal variation. 

"Weismann,  following  the  lead  of  Roux,  interpreted  individual 
modification  in  terms  of  intra-selection.  He  clearly  saw  the  impli- 
cation given  in  4  above.  Speaking  of  'the  well-known  instance  of 
the  gradual  increase  in  the  development  of  deers'  antlers/  he  says 
(Romanes  Lecture,  1894,  p.  18)  :  'It  is  by  no  means  necessary 
that  all  the  parts  concerned  should  simultaneously  adapt  them- 
selves by  variation  of  the  germ  to  the  increase  in  size  of  the  antlers ; 
for  in  each  separate  individual  the  necessary  adaptation  [accommo- 
dation] will  be  temporarily  accomplished  by  intra-selection — by  the 
struggle  of  parts — under  the  trophic  influence  of  functional 
stimulus/ 

"6.  So  far  there  is  no  direct  relation  between  specific  modifications 
and  specific  variations.  Individual  accommodation,  as  a  factor 
in  survival,  affords  time  (Weismann,  op.  cit.,  p.  19)  for  the  occur- 
rence of  any  variations  of  an  adaptive  nature. 

"7.  My  own  modest  contribution  to  the  further  elucidation  of 
the  subject  is  the  suggestion  (i)  that  where  adaptive  variation  v 
is  similar  in  direction  to  individual  modification  m,  the  organism 


OTHER   THEORIES   OF   SPECIES-FORMING.        231 

has  an  added  chance  of  survival  from  the  coincidence  m-\-v;  (2) 
that  where  the  variation  is  antagonistic  in  direction  to  the  modifica- 
tion, there  is  a  diminished  chance  of  survival  from  the  opposition 
m — v-  and  hence  (3)  that  coincident  variations  will  be  fostered 
while  opposing  variations  will  be  eliminated. 

"8.  If  this  be  so,  many  of  the  facts  adduced  by  Lamarckians 
may  be  interpreted  in  terms  of  the  survival  and  gradual  establish- 
ment of  coincident  variations  by  natural  selection  under  the 
favourable  environing  conditions  of  somatic  modifications. 

"g.  It  is  clear  that  there  is  nothing  in  this  suggestion  of  a  direct 
relation  between  specific  accommodation  and  coincident  variation 
which  can  be  antagonistic  to  the  indirect  relation  indicated  above 
in  6. 

"10.  Correlated  and  coexistent  variations  would  have  the  same 
relations  to  coincident  variations  as  obtain  in  other  cases  of  natural 
selection." 


CHAPTER  IX. 

OTHER  THEORIES  OF  SPECIES-FORMING  AND 
DESCENT  (CONTINUED):  AUXILIARY  THE- 
ORIES (CONTINUED). 

Isolation  Theories. — The  varying  importance  attributed 
by  different  biologists  to  the  theories  explaining  means 
and  results  of  isolation  is  notable.  While  by 
some  the  species-forming  influence  of  isolation 
factor  in  species-  js  held  to  be  as  effective  as  selection  itself, — 
some  deem  it  more  effective, — others  attach  but 
little  importance  to  it,  indeed  see  no  effects  of  consequence. 
These  latter  men  are  likely  to  be  morphologists,  cytologists, 
and  laboratory  men  generally;  the  former  are  systematists, 
students  of  distribution,  and  so-called  field  naturalists.  Thus 
Delage,  who  gives  much  attention  in  his  general  discussion 
of  the  theories  of  heredity,  variation,  and  species-forming 
to  many  purely  speculative  theories  of  the  ultimate  structure 
and  behaviour  of  protoplasm,  and  of  the  mechanism  of 
heredity,  dismisses  the  whole  subject  of  geographic  and 
topographic  isolation  with  a  couple  of  superficial  para- 
graphs, in  which  he  presents  a  singularly  fallacious  state- 
ment of  what  the  effects  of  isolation  should  be.  On  the 
other  hand  the  veteran  German  world-voyager  and  exploring 
naturalist,  Moritz  Wagner,  established  long  ago,  on  the  basis 
of  his  observations  and  deductions,  a  "law"  of  species-form- 
ing by  migration  and  consequent  isolation,  which  in  his  mind 
makes  the  natural  selection  theory  superfluous.  And  Henry 
Seebohm  in  a  discussion  of  Romanes's  1  formulation  of  the 
principle  of  physiological  selection,  says:  "So  far  as  is 

232 


OTHER   THEORIES   OF   SPECIES-FORMING.        233. 

known,  no  species  (of  birds)  has  ever  been  differentiated 
without  the  aid  of  geographical  isolation,  though  evolution 
may  have  gone  on  to  an  unknown  extent ;  and,  so  far  as  we 
can  judge,  geographical  isolation  must  always,  sooner  or 
later,  be  followed  by  differentiation."  And  Romanes,  him- 
self, conspicuous  as  the  only  pupil  and  disciple  of  Darwin 
personally  advised  and  aided  by  the  master  himself,  and  one 
of  the  most  brilliant  upholders  and  expositors  of  Darwin- 
ism, says  :2  "Indeed  I  believe  with  Mr.  Gulick,  that  in  the 
principle  of  isolation  we  have  a  principle  so  fundamental 
and  so  universal,  that  even  the  great  principle  of  natural 
selection  lies  less  deep  and  pervades  a  region  of  smaller 
extent.  Equalled  only  in  its  importance  by  the  two  basal 
principles  of  heredity  and  variation,  this  principle  of  isola- 
tion constitutes  the  third  pillar  of  a  tripod  on  which  is  reared 
the  whole  superstructure  of  organic  evolution."  Thus  the 
most  ardent  believers  in  the  effects  of  isolation  find  it,  inde- 
pendent of  selection  and  alone,  sufficient  to  explain  species- 
forming,  while  the  most  ardent  neglecters  of  isolation  theo- 
ries find  them  too  slight  to  be  of  any  consequence  at  all.  We 
shall  take  middle  ground  and  find  in  isolation  a  factor  of 
great  effectiveness  and  one  wide-spread  in  its  influence  in 
helping  to  produce  the  present-day  status  of  the  animal 
kingdom,  but  yet  a  factor  which  shall  most  fairly  be  looked 
on  as  an  auxiliary  or  helping-theory  of  natural  selection.  In 
fact,  to  my  mind,  the  proof  of  the  species-establishing  effects 
of  isolation,  and  of  the  actual  existence  of  isolation  (proof 
of  means  or  modes  of  isolation),  is  something  much  needed 
by  the  general  natural  selection  theory  for  its  own  sup- 
port. Selection  needs  help  from  isolation.  To  my  mind, 
also,  these  means  of  isolation  actually  exist,  and  the  result- 
ing isolation  is  actually  a  very  potent  factor  in  species-form- 
ing. The  proofs  seem  to  me  obvious. 

The  name  isolation  fairly  well  defines  the  condition  that 
we  are  to  discuss ;  (the  term  segregation  has  also  been  used 


234  DARWINISM   TO-DAY. 

by  some  authors  to  name  the  same  condition),  ii,  in  a 
species,  a  number  of  individuals  show  a  certain  congenital 
variation,  this  variation  will  probably  be  lost  by 
cross~breeding  with  individuals  not  having  it, 
unless  the  individuals  having  it  are  in  the  ma- 
jority or  unless  they  become  in  some  way  isolated  from  the 
others  and  segregated  so  that  they  will  breed  among  them- 
selves. By  such  isolation  and  such  in-and-in  breeding  the 
newly  appearing  congenital  variations  might  soon  become 
established,  and  if  advantageous  be  so  considerably  developed 
as  soon  to  distinguish  as  a  variety  or  incipient  species  the 
members  of  the  isolated  colony.  With  time  a  distinct  new 
species  might  result.  Are  there  means  to  produce  such  isola- 
tion of  groups  of  individuals  belonging  to  a  common  species  ? 
The  answer  to  this  is  certainly  an  affirmative  one.  There 
seem  to  be,  indeed,  several  means  of  producing  isolation, 
_  .  and  the  isolation  may  be  variously  named  ac- 

Varions  means 
of  effecting  iso-    cordingly.    Undoubtedly  the  most  important  of 

these  kinds  of  isolation,  at  least  in  the  light  of 
our  present  knowledge,  is  that  known  as  geographical  or 
topographical  isolation.  Isolation  produced  in  other  ways 
may  be  called  biologic  or  physiologic  or  sexual  isolation. 
In  the  case  of  geographic  or  topographic  isolation  the  iso- 
lated group  or  groups  of  individuals  are  actually  in  another 
region  or  locality  from  the  rest  of  the  species,  this  being 
the  result  of  migration,  voluntary  or  involuntary.  In  bio- 
logic isolation  the  individuals  of  the  species  all  inhabit  the 
same  territory  but  become  separated  into  groups  by  struc- 
tural or  physiological  characters  which  prevent 
Wagner  the  miscellaneous  inter-breeding.  The  real  founder 

lonnder  01  the 

theory  of  species- and  most  insistent  upholder  of  the  theory  of 
species-forming  by  isolation  (geographic  and 
topographic  isolation),  was  Moritz  Wagner3 
(1813-1887),  a  traveller  and  naturalist,  whose  wanderings 
and  observations  brought  to  him  the  conviction  that  while 


OTHER   THEORIES   OF   SPECIES-FORMING.        235 

natural  selection  might  modify  species  and  even  produce 
continuous  evolution  it  could  never  differentiate  species, 
that  is,  produce  new  species.  It  could  never,  in  Wagner's 
belief,  produce  the  actual  condition  which  we  know  to  exist 
in  the  present-day  and  past  (now  extinct)  animal  kingdom, 
this  condition  being  the  existence  of  hosts  of  distinct,  though 
related,  animal  species  or  kinds.  Wagner's  travels  included 
journeys  to  North,  Central,  and  South  America,  West  Asia, 
and  North  Africa.  His  first  clear  enunciation  of  his  theory, 
in  which  pronouncement  he  took  definite  stand  against 
the  claimed  capacity  of  Darwinian  selection  to  produce  new 
species,  was  in  1868.  in  a  paper  read  in  Munich,  entitled 
"Die  Darwinische  Theorie  und  das  Migrationsgesetz  der 
Organismen."  From  the  time  of  the  appearance  of  this 
first  paper  until  within  a  year  or  two  of  his  death,  Wagner 
steadily  wrote  and  fought  for  his  theory,  but  without  gain- 
ing for  it  any  such  wide  or  authoritative  acceptance  as  he 
hoped.  In  a  letter  dated  August  30,  1884,  Wagner  pathet- 
ically writes,  "Ich  sterbe  mlt  der  '{jberzeugung,  dass  man 
dies  wenigstens  nach  meinem  Tode  anerkennen  wird" 

Wagner's  theory  included  not  only  the  characteristics 
already  pointed  out  as  the  basis  of  all  theories  of  the  influ- 
ence of  isolation  in  species-forming,  but  the  assumption  that 
all  species  of  animals  have  a  strong  tendency,  or  are  con- 
stantly attempting,  to  "spread  out";  that  is,  have  a  driving 
instinct  of  migration  and  dispersal.  The  basis  of  this 
tendency  is  undoubtedly  the  overcrowding  in  the  immature 
stages  and  in  times  of  short  food-supply  or  untoward  exter- 
nal conditions  of  temperature,  humidity,  etc.  This  tendency 
to  movement  is  Wagner's  "Migrationsgesetz,"  and  the  out- 
come of  it  is  to  bring  about  conditions  of  topographic  and 
geographic  isolation  among  all  kinds  of  animals.  While  in 
his  first  papers  Wagner  looked  on  his  theory  as  a  sort  of 
supporting  or  auxiliary  theory  to  that  of  natural  selection, 
he  soon  began  to  see  in  it,  calling  it  now  by  the  name  of 


236  DARWINISM   TO-DAY. 

"Separationstheorie"  an  independent  and  alternative  expla- 
nation of  species-forming.  In  1870,  he  wrote:*  "Um  den 
Unterschied  beider  Theorien  moglichst  kurz  auszudriicken  : 
nach  der  Darwin'schen  Selectionstheorie  ziichtet  die  Natur 
in  Folge  des  Kampfes  urns  Dasein  rastlos  neue  typische 
Formen  der  Organismen  durch  Auslese  niitzlicher  Varieta- 
ten,  gleichviel  ob  inner-  oder  ausserhalb  des  Verbreitungs- 
gebietes  der  Stammart,  und  kann  diesen  Prozess  der  Bil- 
dung  einer  neuen  Art  nur  innerhalb  eines  sehr  langen 
Zeitraumes  vollziehen. 

"Nach  der  Separationstheorie  ziichtet  die  Natur  nur 
periodisch  neue  Formen  stets  ausserhalb  des  Wohngebietes 
der  Stammart  durch  geographische  Isolierung  und  Kolo- 
nienbildung,  ohne  welche  bei  alien  hoheren  Tieren  getrenn- 
ten  Geschlechts  keine  konstante  Varietat  oder  neue  Art 
entstehen  kann.  Der  Gestaltungsprozess  einer  neuen  Form 
kann  nicht  von  langer  Dauer  sein." 

Or  in  still  more  condensed  form  :5  .  .  .  "Nach  der  Selek- 
tionstheorie  ist  der  Kampf  urns  Dasein,  nach  der  Separa- 
tionstheorie die  raumliche  Absonderung,  die  nachste  zwing- 
ende  Ursache  der  Artbildung." 

Wagner's  latest,  most  definitive,  cleanest  cut,  single 
formulation  of  the  Separationstheorie  is  that  contained  in 
two  paragraphs  in  his  essay  entitled,  "Leopold  von  Buch 
und  Charles  Darwin"  (Kosmos,  1883).  These  paragraphs 
are  the  following : 

"i.  Jede  dauernde  raumliche  Absonderung  einzelner  oder 
weniger  Emigranten  von  einer  Stammart,  welche  noch  im 
Stadium  der  Variationsfahigkeit  steht,  erzwingt  auf  Grund 
der  Variabilitat  und  der  Vererbung  eine  konstante  Diffe- 
renzierung,  indem  sie  unter  Mitwirkung  veranderter  Le- 
bensbedingungen,  die  jeden  Standortswechsel  begleiten, 
auch  die  minimalsten  individuellen  Merkmale  der  ersten 
Kolonisten  bei  blutsverwandter  Fortpflanzung  fortbildet 
und  befestigt. 


OTHER   THEORIES   OF  SPECIES-FORMING.        237 

"2.  Keine  konstante  Varietat  oder  Art  entsteht  ohne 
Ausscheidung  einzelner  oder  weniger  Individuen  von  der 
Stammart  und  ohne  Ansiedelung  an  einem  neuen  Standort, 
well  Massenkreuzung  und  Gleichheit  der  Lebensbedin- 
•gungen  in  einem  zusammenhangenden  Wohngebiet  immer 
absorbierend  und  nivellierend  wirken  mtissen  und  indivi- 
duelle  Variationen  stets  wieder  in  die  Stammform  zuriick- 
drangen." 

Wagner's  6  long  series  of  interesting  papers  and  addresses 
are  crammed  with  facts  of  plant  and  animal  geography, 
taxonomy  and  palaeontology,  and  with  keen  interpretation 
of  these  facts,  and  clear  and  incisive  formulations  of  his  few 
generalisations. 

One  of  the  most  ardent  present-day  upholders  of  the 
species-forming  potency  of  geographical  isolation  is  David 
Starr  Jordan,  the  foremost  American  student  of  the  classi- 
fication and  distribution  of  fishes.  From  a  recent  paper  7 
I  abstract  the  following  brief  statements  of  his  beliefs  con- 
cerning the  character  and  results  of  the  influence  of  geo- 
graphical isolation. 

"It  is  now,"  writes  Jordan,  "nearly  forty  years  since 
Moritz  Wagner  (1868)  first  made  it  clear  that  geographical 
isolation  (rdiimliche  Sonderung)  was  a  factor 
geographic  or  condition  in  the  formation  of  every  species, 
isolation,  race,  or  tribe  of  animal  or  plant  we  know  on 

the  face  of  the  earth.  This  conclusion  is  accepted  as  almost 
self-evident  by  every  competent  student  of  species  or  of 
the  geographical  distribution  of  species.  But  to  those  who 
approach  the  subject  of  evolution  from  some  other  side  the 
principles  set  forth  by  Wagner  seem  less  clear.  They  have 
never  been  confuted,  scarcely  even  attacked,  so  far  as  the 
present  writer  remembers,  but  in  the  literature  of  evolution 
of  the  present  day  they  have  been  almost  universally  ignored. 
Nowadays  much  of  our  discussion  turns  on  the  question  of 
•whether  or  not  minute  favourable  variations  would  enable 


238  DARWINISM   TO-DAY. 

their  possessors  little  by  little  to  gain  on  the  parent  stock, 
so  that  a  new  species  would  be  established  side  by  side  with 
•  the  old,  or  on  whether  a  wide  fluctuation  or  mutation  would 
give  rise  to  a  new  species  which  would  hold  its  own  in  com- 
petition with  its  parent.  In  theory,  either  of  these  condi- 
tions might  exist.  In  fact,  both  of  them  are  virtually  un- 
known. In  nature  a  closely  related  distinct  species  is  not 
often  quite  side  by  side  with  the  old.  It  is  simply  next  to  it, 
geographically  or  geologically  speaking,  and  the  degree  of 
distinction  almost  always  bears  a  relation  to  the  importance 
or  the  permanence  of  the  barrier  separating  the  supposed 
new  stock  from  the  parent  stock. 

"A  flood  of  light  may  be  thrown  on  the  theoretical  prob- 
lem of  the  origin  of  species  by  the  study  of  the  probable 
actual  origin  of  species  with  which  we  may  be  familiar,  or 
of  which  the  actual  history  or  the  actual  ramifications  may 
in  some  degree  be  traced." 

Dr.  Jordan  then  proceeds  to  relate  and  analyse  our  pres- 
ent actual  knowledge  of  the  make-up  of  certain  local  faunae, 
of  the  migrations  and  distribution  of  certain  well-known 
animal  species  (especially  in  the  phyla  of  birds  and  fishes, 
in  which  groups  our  knowledge  of  the  present  status  in 
North  America  of  species  and  varieties  and  their  distribu- 
tion is  nearly  exhaustive),  and  of  the  climatic,  topographic, 
and  general  geographic  barriers  8  which  determine  this  dis- 
tribution, in  a  way  most  convincing  to  unprejudiced  minds. 
He  brings  to  the  support  of  his  own  statements  of  fact  and 
opinion  the  testimony  (contained  in  personal  letters  an- 
swering direct  queries  from  himself)  of  many  well-known 
American  students  of  systematic  and  faunistic  zoology. 
Jordan  sums  up  the  results  of  his  display  of  North  Ameri- 
can faunal  conditions  in  various  paragraphs,  from  among 
which  the  following  are  quoted : 

"In  regions  broken  by  few  barriers,  migration  and  inter- 
breeding being  allowed,  we  find  widely  distributed  species* 


OTHER   THEORIES   OF   SPECIES-FORMING.        239 

homogeneous  in  their  character,  the  members  showing  indi- 
vidual fluctuation  and  climatic  effects,  but  remaining  uni- 
form in  most  regards,  all  representatives  slowly  changing 
together  in  the  process  of  adaptation  by  natural  selection. 
In  regions  broken  by  barriers  which  isolate  groups  of  indi- 
viduals we  find  a  great  number  of  related  species,  though  in 
most  cases  the  same  region  contains  a  smaller  number  of 
genera  or  families.  In  other  words,  the  new  species  will  be 
formed  conditioned  on  isolation,  though  these  same  barriers 
may  shut  out  altogether  forms  of  life  which  would  invade 
the  open  district. 

"Given  any  species  in  any  region,  the  nearest  related 
species  is  not  likely  to  be  found  in  the  same  region  nor  in 
a  remote  region,  but  in  a  neighbouring  district  separated 
from  the  first  by  a  barrier  of  some  sort. 

"Doubtless  wide  fluctuations  or  mutations  in  every  species 
are  more  common  than  we  suppose.  With  free  access  to  the 
mass  of  the  species,  these  are  lost  through  interbreeding. 
Isolate  them  as  in  a  garden  or  an  enclosure  or  on  an  island, 
and  these  may  be  continued  and  intensified  to  form  new 
species  or  races.  Any  horticulturist  will  illustrate  this. 

"In  these  and  in  all  similar  cases  we  may  confidently 
affirm :  The  adaptive  characters  a  species  may  present  are 
due  to  natural  selection  or  are  developed  in  connection  with 
the  demands  of  competition.  The  characters,  non-adaptive, 
which  chiefly  distinguish  species  do  not  result  from  natural 
selection,  but  from  some  form  of  geographical  isolation  and 
the  segregation  of  individuals  resulting  from  it. 

"In  the  animal  kingdom,  generally,  we  may  say:  When- 
ever a  barrier  is  to  some  extent  traversable,  the  forms 
separated  by  it  are  liable  to  cross  from  one  side  to  the  other, 
thus  producing  intergradations,  or  forms  more  or  less 
intermediate  between  the  one  and  the  other.  For  every 
subspecies,  where  the  nature  of  the  variation  has  been  care- 
fully studied,  there  is  always  a  geographical  basis.  This 


240  DARWINISM   TO-DAY. 

basis  is  defined  by  the  presence  of  some  sort  of  a  physical 
barrier.  It  is  extremely  rare  to  find  two  subspecies  inhabit- 
ing or  breeding  in  exactly  the  same  region.  When  such 
appears  to  be  the  case,  there  is  really  some  difference  in 
habit  or  in  habitat ;  the  one  form  lives  on  the  hills,  the  other 
in  the  valleys;  the  one  feeds  on  one  plant,  the  other  on 
another;  the  one  lives  in  deep  water,  the  other  along  the 
shore.  There  can  be  no  possible  doubt  that  subspecies  are 
nascent  species,  and  that  the  accident  of  intergradation  in 
the  one  case  and  not  in  the  other  implies  no  real  difference 
in  origins. 

"To  the  general  rule  that  closely  allied  species  do  not  live 
together  there  exist  partial  exceptions.  It  may  be  well  to 
glance  at  some  of  these,  for  no  rule  is  established  until  its 
exceptions  are  brought  into  harmony  with  the  phenomena 
which  illustrate  the  rule."  (Here  Dr.  Jordan  details  the 
facts  of  distribution  in  three  cases  from  among  the  fishes, 
which  apparently  form  exceptions  to  his  general  rule). 

As  an  example  of  the  effects  of  an  unusual  and  interesting 
phase  of  isolation  I  may  refer  to  the  conditions  noted  con- 
cerning the  distribution  and  species  distinction 
isolation  in  the  of  the  Mallophaga,  a  group  of  small  wingless 
Mailophaga.  jnsect  parasites  on  birds  and  mammals.  These 
parasites  live  for  their  whole  lives  among  the  feathers  or 
hair  of  their  hosts,  and  while  able  to  run  swiftly  are  unable 
to  fly  and  thus  to  migrate  freely  from  bird  to  bird. 

"There  are  to  be  noted  various  results  of  the  influence  on 
the  taxonomy  of  the  Mallophaga  of  the  peculiar  conditions 
of  their  parasitic  life.  While  the  uniformity  and  persistence 
of  the  conditions  under  which  the  life  of  the  parasites  is 
passed  tend  to  preserve  with  little  change  the  species  types, 
the  peculiar  isolation,  often  pretty  complete,  of  groups  of 
individuals  of  a  parasite  species  on  individual  birds  of  the 
host  species  and  the  consequent  close  breeding,  tend  to 
foster  and  fix  those  inevitable  slight  variations  always  mani- 


OTHER   THEORIES    OF   SPECIES-FORMING.        241 

fest  in  a  comparison  of  offspring  and  parents,  but  under 
normal  conditions  held  in  check  or  lost  (unless  directly 
advantageous)  by  crossing  among  less  closely  related  indi- 
viduals. For  example,  the  individuals  of  a  parasite  species 
on  a  bird  of  long  life  and  non-gregarious  and  monogamous 
habits,  like  an  eagle,  live  very  much  the  life  of  an  isolated 
community.  There  must  be  many  years  of  in-and-in  breed- 
ing. It  is  like  island  life.  The  result  is  certain  :  the  members 
of  this  isolated  group  will  soon  differ  from  the  specific 
type  in  noticeable  particulars.  On  the  other  hand,  the  con- 
ditions of  life  on  this  'island'  are  practically  identical  with 
the  conditions  on  other  similar  'islands' — other  eagles — in- 
habited by  other  individuals  of  the  same  parasite  species,  so 
there  is  no  influence  working  to  produce  a  wide  divergence 
of  the  members  of  these  various  isolated  groups  of  indi- 
viduals of  the  same  species.  Now  this  isolation  of  groups  of 
individuals  is  in  some  degree  an  incident  of  the  life  of  all 
Mallophaga;  in  some  instances  it  is  considerable;  in  others, 
inconsiderable,  but  taken  altogether  a  condition  in  the  life 
of  the  whole  order  exerting  an  influence  which  has  the 
readily  recognisable  result  of  creating  a  great  number  of 
small  variations  within  species  limits. 

"The  results,  manifest  to  any  student  of  the  group,  of 
these  two  opposing  influences  are  to  render  difficult  the  divi- 
sion of  the  order  into  distinct  genera  on  account  of  the  gen- 
eral similarity  of  structure,  and  to  make  difficult  the  defini- 
tion of  species  on  account  of  the  many  slight  variations 
among  the  individuals  from  different  bird  individuals." s 

The  study  of  geographic  distribution  and  its  influences  on 
species-forming  has  not  been  limited,  of  course,  to  living 
Geographic  organisms  alone.  In  fact,  the  geologic  study 
Im^ast1^64  of  distribution  and  migration  of  both  animals 
animals,  and  plants  has  given  us  some  of  our  most 

important  facts  touching  the  problem  of  the  influence  of 
isolation  on  species-transformation.  In  an  interesting  paper 


242  DARWINISM   TO-DAY. 

on  the  "geological  study  of  the  migration  of  marine  inverte- 
brates," Smith  10  has  pointed  out  the  general  principles  and 
conditions  upon  which  the  interpretation  of  the  geographic 
distribution  of  the  marine  invertebrates  of  the  earlier  geo- 
Jogic  ages  must  be  based. 

In  closing  this  consideration  of  the  status  of  geographic 
isolation  as  a  factor  in  species-forming,  I  should  not  omit  to 
Isolation  not     call  attention  to  the  fact,  which  should  be  obvi- 
a^nt "off SB-  ous  enough  to  any  reader,  that  isolation  in  itself 
forming.  cannot  be  the  basic  and  all-sufficient  cause  for 

the  production  of  specific  differentiation,  any  more  than  any 
selective  factor  can.  The  prerequisite  in  both  cases  is  the 
occurrence  of  variation.  What  are  the  variations,  and  how 
are  they  produced :  these  are  the  fundamental  questions  in 
species-forming.  Isolation  is  a  tremendously  favouring  con- 
dition but  not  a  primary  cause  of  species-forming.  It  tends 
to  help  along,  to  hurry  up  species  disintegration,  not  to 
initiate  it.  It  is  a  biological  catalytic  agent. 

In  this  present  connection  the  pertinent  question  is,  is  the 
influence  of  geographical  isolation  in  the  cumulation  of 
variation  or  intra-specific  differentiation  due  to  its  com- 
pelling in-and-in  breeding  and  hence  the  fostering  and  cumu- 
lation of  fortuitous  Darwinian  variations  occurring  in  the 
comparatively  few  individuals  of  the  isolated  group,  or  is 
there  a  spur  to  variation,  or  even  actual  production  of  it  along 
determinate  lines,  in  the  new  environmental  conditions  com- 
mon to  all  the  isolated  group  but  inevitably  different  from 
the  conditions  to  which  the  parent  type  is  exposed  ?  Is  there 
a  gradual  accumulation  of  differences  between  the  split-off 
group  and  the  parent  group  due  to  environmental  influence 
plus  in-and-in  breeding?  If  we  could  reply  yes  to  this 
question,  we  should  have  a  sufficient  explanation  of 
how  the  isolated  group  splits  rapidly  away  in  many 
small,  and  in  a  few  large,  characteristics  from  the  parent 
stock. 


OTHER   THEORIES   OF    SPECIES-FORMING.        243 

From  the  foregoing  it  is  obvious  that  geographical  isola- 
tion is  a  proved,  effective,  and  widely  applied  species-form- 
ing factor.    So  much  cannot  be  said  for  biologic 
Biologic          and  sexltai  isolation.11     The  actual  existence  of 

isolation, 

such  isolation  is  not  proved  by  any  mass  of  evi- 
dence based  on  observation,  although  the  theory  is  by  no 
means  pure  speculation;  nor  are  the  results  of  such  isola- 
tion clearly  indicated,  although  a  certain  amount  of  observa- 
tion and  experimental  evidence  can  be  adduced  to  show 
them.  The  different  phases  of  isolation,  not  geographic, 
called  by  different  names,  as  biologic,  physiolpgic,  sexual, 
and  morphologic  isolation,  all  have  reference  to  some  sort 
of  segregation  of  individuals  of  the  same  species  into  groups 
inside  of  each  of  which  mating  takes  place,  and  among 
which  little  or  no  cross-breeding  occurs,  because  of  varying 
habits,  or  unusual  sexual  aversion  or  attraction,  or  physio- 
logical or  morphological  variation  affecting  mating.  For 
example,  to  take  first  a  sort  of  combination  of  geographic 
and  biologic  isolation,  Plate 12  points  out  that  there  are 
twelve  species  of  albatrosses  in  the  southern  hemisphere,  of 
which  nine  or  ten  belong  to  the  Australian  zoo-geographical 
realm  and  intermingle  throughout  most  of  their  range.  At 
breeding  time,  however,  these  different  species  become 
segregated  in  restricted  and  separate  localities  so  that  mating 
is  always  accomplished  among  different  individuals  of  the 
same  species,  although  hybridisation  could  doubtless  obtain 
successfully  among  these  closely  related  albatross  forms. 
Thus  the  species  characters  are  kept  pure;  the  species  dis- 
tinct. 

An  example  of  pure  biological  isolation  and  one  within 

a  single  species  (which  is  the  sort  of  isolation  we  are  more 

An  example  of  interested  in)  might  be  produced  in  the  follow- 

loTatioSght    inS  wa^     We  know  of  numerous  species  of 
work,  butterflies  which  appear  in  different  seasons  of 

the  year  in  different  colour-pattern.     This  is  not  a  colour 


244  DARWINISM   TO-DAY. 

change  in  individuals  but  results  from  an  earlier  or  later 
hatching  of  eggs  laid  in  the  autumn  or  summer  before. 
These  eggs  may,  indeed,  be  all  of  one  batch  or  lot,  laid  by  a 
single  female.  Some  of  these  eggs  hatch  in  the  spring ;  the 
butterflies  that  come  from  these  spring  larvse  are  of  one  col- 
our-pattern ;  some  of  the  eggs,  however,  delay  hatching  until 
summer;  from  these  larvse  come  butterflies  of  another 
colour-pattern;  some  of  the  eggs  even  go  over  until  fall 
before  hatching ;  these  latest  butterfly  individuals  may  be  of 
a  third  colour-pattern.  The  colour-pattern  here  must  have 
some  fixed  relation  to  the  time  or  season  of  hatching  of  the 
eggs ;  it  is  not  a  result  of  isolation.  But  the  condition  well 
illustrates  the  actual  existence  of  a  biological  isolation  within 
a  species :  the  spring  butterflies  must  mate  among  them- 
selves, the  summer  individuals  among  themselves,  and  the 
fall  butterflies  among  themselves.  Within  the  one  species 
are  three  biologically  isolated  groups  of  individuals  re- 
strained from  inter-breeding.  Suppose  the  individuals  of 
a  bird  species  show  among  themselves  a  tendency  to  vary 
in  their  breeding  time ;  some  are  ready  to  breed  early,  others 
delay  mating.  Roughly  segregated  into  two  groups,  early 
breeders  and  late,  the  individuals  of  the  two  groups  would 
obviously  tend  to  breed  each  inside  its  own  group.  Hut- 
ton  1S  actually  records  the  occurrence  of  two  varieties  of  the 
shore-bird,  (Estrelata  neglecta,  in  the  Kermadec  Islands, 
which  live  together  but  breed  at  different  times.  A  pelagic 
crustacean  living  near  the  shore  increases  rapidly  in  num- 
bers ;  some  individuals  find  themselves  able  to  live  on  the 
shore  in  pools  between  tide-lines.  The  pool  dwellers  breed 
together :  the  pelagic  individuals  breed  together ;  a  biologic 
isolation — in  truth  an  isolation  partly  topographic — might 
soon  come  to  exist.  Any  variation  in  habits  of  life  among 
individuals  living  in  the  same  locality,  which  tends  to  deter- 
mine that  breeding  shall  be  roughly  restricted  within  cer- 
tain groups  produces  biologic  isolation ;  such  variation  might 


OTHER  THEORIES   OF   SPECIES-FORMING.        245 

be  a  variance  in  sexual  maturity,  a  change  in  breeding  time 
for  that  or  any  other  reason,  a  tendency  on  the  part  of  cer- 
tain individuals  to  live  more  or  less  concealed  in  holes,  under 
stones,  etc.,  changes  in  food-habits,  as  the  gradual  going 
over  of  some  individuals  of  a  plant-feeding  insect  species 
from  the  old  food-plant  to  a  new  one,  or  the  tendency  within 
an  omnivorous  species  for  groups  to  restrict  themselves  to 
certain  specific  foods :  all  such  variations  might  lead  to  pos- 
sible biological  isolation. 

By  sexual  isolation  authors  usually  refer  to  the  influ- 
ence of  some  variation  tending  to  make  difficult  or  impossi- 
Semal  ble  wholly  free  and  miscellaneous  mating  or 

isolation,  breeding  inside  of  a  species.     This  variation 

may  be  of  purely  physiological  character  or  may  be  a  struc- 
tural one :  that  is,  the  hindrance  to  mating  may  be  one  of 
instinctive  feeling,  a  "race-feeling"  depending  on  an  antipa- 
thy to  odour,  to  age,  to  appearance,  etc.,  or  may  be  a  slight 
modification  of  the  copulatory  organs  making  such  mating 
difficult,  or  even  a  modification  of  the  egg  or  the  spermato- 
zoids  making  fertilisation  difficult.  It  is  a  well-known  fact 
that  numerous  varieties  of  domesticated  animal  species 
rarely  breed  together,  although  quite  able  to,  and  provided 
with  full  opportunity.  On  the  other  hand,  animals  of  differ- 
ent species  which  in  Nature  rarely  or  never  breed  together 
may,  if  kept  long  in  confinement,  as  in  zoological  gardens, 
mate  14  and  produce  young.  In  each  case  there  seems  to  be 
question  of  a  "race-feeling" ;  in  the  first  case  a  sexual 
aversion  keeping  apart  individuals  of  the  same  species,  in 
the  second  the  breaking  down  of  race-feeling  that  in  Nature 
has  sufficed  to  prevent  hybridising.  This  might  be  termed 
physiological  isolation,  or,  indeed,  physiological  selection,  as 

it  has  been  called,  and  given  much  credit  for 
8elPectyion!°giCal    species-forming    by    Romanes15    and    others. 

Romanes  and  Hutton  believe  that  a  progressive 
infertility  results  in  this  way  (and  also  by  the  way  referred 


246  DARWINISM   TO-DAY. 

to  in  the  next  paragraph)  which  can  soon  result  in  complete 
infertility,  hence  specific  distinctness  on  the  part  of  the 
mutually  infertile  groups. 

Mutual  infertility   due   to   morphological   variations   has 
been  called  "mechanical  selection"  by  Karl  Jordan,19  and 

may  rest  on  slight  variations  in  germ-cells  or 
selection"™1       copulatory    structures.       Such    morphological 

variations  of  the  reproductive  organs  have  been 
believed  to  be  shown  for  butterflies  and  spiders,  while  the 
delicate  tropismic  responses  of  the  active  spermatozoids  to 
the  attracting  chemical  substances  in  the  egg-cells  of  echino- 
derms,  ccelenterates,  molluscs,  and  fishes  have  been  thought 
to  be  conditions  in  which  a  slight  chemical  or  physical  varia- 
tion might  have  a  large  influence  in  preventing  or  insuring 
fertilisation.  Indeed,  when  one  examines  comparatively  the 
curiously  various  complex  accessory  reproductive  organs 
(claspers,  gonapophyses,  intromittent  organs,  etc.)  of  almost 
any  group  of  insects,  one's  first  thought  is  that  this  variety 
must  practically  effectually  exclude  all  possibility  of  hybri- 
dising. But  the  interesting  detailed  comparative  studies 
by  Snodgrass  1T  of  the  accessory  genitalia  in  various  families 
of  Diptera  make  this  confidence  less  certain.  In  the  large 
family  Tipulidae,  for  example,  he  finds  great  complexity 
and  remarkable  variety  (among  the  different  closely  allied 
species)  in  this  complexity  in  the  genitalia  of  the  males,  but 
almost  no  variation  at  all  in  the  corresponding  (complement- 
ary) parts  of  the  females.  "Throughout  the  entire  family 
the  females  present  one  type  of  structure,  of  which  there  is 
but  little  modification,  and  certainly  none  to  correspond  with 
the  great  variety  of  specific  differences  found  in  the  genitalia 
of  the  males."  Now  while  the  great  variety  of  the  copula- 
tory parts  would  be  extremely  significant  if  shared  by  both 
sexes  so  that  only  one  kind  of  key  could  fit  one  kind  of  lock, 
we  have  the  inexplicable  condition  actually  existing  of  the 
keys  being  extremely  various  and  complex,  but  the  locks  all 


OTHER   THEORIES   OF   SPECIES-FORMING.        247 

being  so  similar  and  simple  that  any  bent  nail  is  able  to  pick 
them. 

Seebohm  18   criticises  Romanes's  theory  of  physiological 

selection,    which    should    better    be    called    physiological 

Seebohm's        isolation,  as  demanding  an  almost  impossible 

criticism  of         coincidence    of   conditions    to    make    it    work. 

physiologic  se- 
lection. Formulated  as  nearly  as  it  can  be  in  a  single 

sentence,  Romanes  has  defined  physiological  selection  as 
follows :  "Wherever,  among  all  the  possible  variations  of 
the  highly  variable  reproductive  system  there  arises  toward 
any  parent  form  any  degree  of  sterility  which  does  not 
extend  to  the  varietal  form,  there  a  new  species  must  neces- 
sarily take  its  origin."  Seebohm  points  out  that  this  is 
exactly  a  condition  that  can  rarely,  if  ever,  occur,  for  to 
bring  it  about  we  must  presuppose : — 

"ist.  The  special  variation  of  the  reproductive  organs 
must  occur  in  two  individuals,  otherwise  the  possible  an- 
cestor of  the  new  species  would  leave  no  descendants. 

"2d.  It  must  occur  at  the  same  time  in  both. 

"3d.  It  must  occur  at  the  same  place. 

"4th.  The  two  individuals  must  be  of  opposite  sexes. 

"5th.  They  must  each  of  them  possess  some  other  varia- 
tion, or  their  progeny  would  not  differ  from  that  of  the  rest 
of  the  species. 

"6th.  The  variation  must  be  the  same  in  both  or  appear 
simultaneously  in  the  majority  of  their  children,  otherwise 
it  would  be  swamped  by  interbreeding  within  the  physio- 
logically isolated  family." 

Romanes's  theory  has  also  been  strongly  criticised  by 
Wallace  19  and  by  Karl  Jordan.20  Wallace  contends  that 

Other  criticisms  "no  ^orm  °*  infertmtv  or  sterility  between  the 
ofEomanes's  individuals  of  a  species  can  be  increased  by 

eory>  natural  selection  unless  correlated  with  some 

useful  variation,  while  all  unfertility  not  so  correlated  has  a 
constant  tendency  to  effect  its  own  elimination.  But  the 


248  DARWINISM    TO-DAY. 

opposite  property,  fertility,  is  of  vital  importance  to  every 
species,  and  gives  the  offspring  of  the  individuals  which 
possess  it,  in  consequence  of  their  superior  numbers,  a 
greater  chance  of  survival  in  the  battle  of  life.  It  is,  there- 
fore, indirectly  under  the  control  of  natural  selection,  which 
acts  both  for  the  self-preservation  of  fertile  and  the  self- 
destruction  of  unfertile  stocks — except  always,  as  correlated 
above,  when  they  become  useful  and  therefore  subject  to  be 
increased  by  natural  selection."  Jordan  maintains  that  the 
outcome  of  physiological  selection  can  be  at  best  only 
dimorphism,  not  specific  distinctness. 

Vernon  21  has  formulated  a  theory  which  he  calls  that  of 
"reproductive  divergence,"  in  the  following  words:  "Sup- 
Vemon's         posing  that  among  the  members  of  any  species 
ductive^er-0"    tnose  individuals  more  alike  in  respect  to  any 
gence.  different  characteristic,  such  as  colour,  form,  or 

size,  are  slightly  more  fertile  inter  se  than  less  similar  indi- 
viduals, it  necessarily  follows  that  in  the  course  of  succeed- 
ing generations  the  members  of  this  species  will  diverge 
more  and  more  in  respect  to  the  characteristic  in  question, 
whereby  ultimately  the  original  species  may  be  split  up  into 
two  or  more  fresh  species."  As  a  concrete  example,  Vernon 
supposes  that  in  the  Lepidopterous  Ithania  urolina,  a  certain 
insect  found  in  the  Amazon  Valley,  small  individuals  were 
slightly  more  fertile  with  other  small  individuals  than  with 
large  individuals,  while  these  were  also  more  fertile  inter  se; 
"then  it  would  follow  that  fewer  individuals  of  intermediate 
size  would  be  produced,  and  in  course  of  time  the  species 
would  be  split  up  into  a  small  and  large  variety.  These 
varieties  would  continue  to  diverge  as  long  as  the  process 
of  'reproductive  divergence'  was  acting,  till  at  length  they 
might  become  differentiated  in  the  two  mutually  sterile 
species.  Supposing  on  the  other  hand  this  variation  in 
fertility  were  correlated  with  slight  differences  of  colour, 
then  in  course  of  time  varieties  differing  in  respect  of  colour 


OTHER   THEORIES   OF   SPECIES-FORMING.        249 

would  be  produced;  or  if  it  were  correlated  with  both  size 
and  colour,  varieties  differing  in  respect  of  both  characters 
might  be  produced.  As  a  matter  of  fact,  this  insect  does 
actually  occur  as  four  distinct  varieties  differing  in  colour, 
form,  and  size,  though  whether  in  consequence  of  the  oper- 
ation of  reproductive  divergence  it  is  of  course  impossible 
to  say."  But  this  theory  has  been  strongly  criticised  by 
Karl  Jordan,22  who  believes  himself  able  to  show  that  re- 
productive divergence  would  not  work  in  the  way  conceived 
by  Vernon,  but  actually  in  such  a  way  as  to  establish  an 
intermediate  form. 

Karl  Pearson  23  has  formulated  a  theory  called  "reproduc- 
tive selection"  which  he  believes  to  be  distinct  from  both  the 
_        .          Romanes  and  the  Vernon  theories,  and  to  which 

Pearson's 

theory  of  repro-  he  attributes  an  importance  in  evolution  'equi- 
ductive  selection,  potent  tQ  natural  selection,  if  indeed  it  be  not 

prepotent."  The  theory  is  based  on  correlations  which  seem 
to  exist  between  the  variation  in  some  particular  organ  and 
fertility.  From  studies  of  variation  of  height  in  4,000  Anglo- 
Saxon  families  and  1,182  Danish  families,  Pearson  finds 
that  there  exists  a  distinct  correlation  between  fertility  and 
height  in  the  mothers  of  daughters  in  these  families.  The 
effect  of  this  correlation  is  to  render  women  less  variable 
and  to  raise  their  mean  height.  The  quantities  are  small, 
but  are  sufficient,  if  unchecked  by  natural  selection,  to  raise 
the  mean  height  of  women  in  forty  generations  by  3  1-4 
inches.  "A  factor  which  would  alter  stature  by  about  three 
inches  in  1,000  years  is  clearly  capable  of  producing  very 
considerable  results  in  the  long  periods  during  which  evolu- 
tion may  be  supposed  to  have  been  at  work." 

Of  large  importance  in  any  consideration  of  the  relations 

Gnlick's  im-      of  isolation  to  species-forming  are  the  observa- 

portantobserva-  tions  and  conciusions  of  Gulick.    Derived  origi- 

tions  and  concln-  ° 

sions.  nally  from  an  exhaustive  study  of  the  variation 

and  life-conditions  of  certain  land  shells    (Achatinellidae) 


DARWINISM   TO-DAY. 

in  the  Hawaiian  Islands,  he  formulated,  in  1872,  an  im- 
portant principle  concerning  the  species-differentiating  ef- 
fects of  indiscriminate  isolation.  As  Romanes  2t  well  points 
out,  isolation  may  not  only  admit  of  degrees,  that  is, 
may  be  either  total  or  partial,  and,  if  partial,  may  occur 
in  numberless  grades  of  efficiency,  but  it  may  be  either  dis- 
criminate or  indiscriminate.  If  it  be  discriminate,  the  isola- 
tion has  reference  to  the  resemblance  of  the  separated  indi- 
viduals to  one  another ;  if  it  be  indiscriminate,  it  has  no  such 
reference.  For  example,  if  a  shepherd  divides  a  flock  of 
sheep  without  regard  to  their  characters,  he  is  isolating  one 
section  from  the  other  indiscriminately;  but  if  he  places  all 
the  white  sheep  in  one  field  and  all  the  black  sheep  in  another 
field,  he  is  isolating  one  section  from  the  other  discriminately. 
Or,  if  geological  subsidence  divides  a  species  into  two  parts, 
the  isolation  will  be  indiscriminate ;  but  if  the  separation  be 
due  to  one  of  the  sections  developing,  for  example,  a  change 
of  instinct  determining  migration  to  another  area,  or  occu- 
pation of  a  different  habitat  on  the  same  area,  then  the  isola- 
tion will  be  discriminate,  so  far  as  the  resemblance  of  instinct 
is  concerned.  Discriminate  isolation  has  been  called  by 
•Gulick  segregate  breeding,  and  indiscriminate  isolation  sepa- 
rate breeding. 

Now  the  effectiveness  of  discriminate  isolation  or  segre- 
gate breeding,  however  effected,  to  produce  species-differ- 
entiation is  of  course  obvious.  In  fact,  as  Romanes  points 
out,  it  is  only  when  assisted  by  some  form  of  discriminate 
isolation  which  determines  the  exclusive  breeding  of  like 
with  like,  that  heredity  can  make  in  favour  of  change  of 
type  or  lead  to  what  we  understand  by  organic  evolution. 
But  what  about  indiscriminate  isolation  ?  Does  it  not  seem, 
at  first  sight  at  least,  that  this  kind  of  isolation  must  count 
for  nothing  in  the  process  of  evolution  ?  Is  it  not  apparently 
self-evident  that  the  farmer  who  separated  his  stock  into  two 
or  more  parts  indiscriminately,  would  not  effect  any  more 


OTHER   THEORIES   OF   SPECIES-FORMING.        251 

change  in  his  stock  than  if  he  had  left  them  all  to  breed 
together  ? 

"Well,"  says  Romanes,  "although  at  first  sight  this  seems 
self-evident,  it  is  in  fact  untrue.  For,  unless  the  individuals 
which  are  indiscriminately  isolated  happen  to  be  a  very  large 
number,  sooner  or  later  their  progeny  will  come  to  differ 
from  that  of  the  parent  type,  or  unisolated  portion  of  the 
previous  stock.  And,  of  course,  as  soon  as  this  change  of 
type  begins,  the  isolation  ceases  to  be  indiscriminate :  the 
previous  apogamy  [indiscriminate  isolation]  has  been  con- 
verted into  homogamy  [discriminate  isolation],  with  the 
usual  result  of  causing  a  divergence  of  type.  The  reason 
why  progeny  of  an  indiscriminately  isolated  section  of  an 
originally  uniform  stock — e.  g.,  of  a  species — will  eventually 
deviate  from  the  original  type  is,  to  quote  Mr.  Gulick,25  as 
follows :  "No  two  portions  of  a  species  possess  exactly  the 
same  average  character,  and,  therefore,  the  initial  differ- 
ences are  for  ever  reacting  on  the  environment  and  on  each 
other  in  such  a  way  as  to  ensure  increasing  divergence  as 
long  as  the  individuals  of  the  two  groups  are  kept  from 
intergenerating." 

Gulick  was  led  to  his  recognition  of  the  principle  in  ques- 
tion, not  by  any  deductive  reasoning  from  general  principles, 
Gulick's  stud  ^ltt  ^v  ms  own  particular  and  detailed  observa- 
ies  of  Hawaiian  tions  of  the  land  mollusca  of  the  Sandwich 
land-snails,  islands.  Here  there  is  an  immense  number 
of  varieties  belonging  to  several  genera ;  but  every  variety 
is  restricted,  not  merely  to  the  same  island,  but  actually 
to  the  same  valley.  Moreover,  on  tracing  this  fauna 
from  valley  to  valley,  it  is  apparent  that  a  slight  varia- 
tion in  the  occupants  of  valley  2  as  compared  with  those 
of  the  adjacent  valley  I,  becomes  more  pronounced  in 
the  next  valley  3,  still  more  so  in  4,  etc.,  etc.  Thus  it 
was  possible,  as  Mr.  Gulick  says,  roughly  to  estimate  the 
amount  of  divergence  between  the  occupants  of  any 


252  DARWINISM   TO-DAY. 

two  given  valleys  by  measuring  the  number  of  miles  be- 
tween them. 

On  the  basis  of  his  detailed  observations,  Gulick28  has 
proposed  the  following  three  general  propositions  as  to  the 
relations  of  isolation  to  species-forming: 

"i.  A  species  exposed  to  different  conditions  in  the  differ- 
ent parts  of  the  area  over  which  it  is  distributed,  is  not 
represented  by  divergent  forms  when  free  inter-breeding 
exists  between  the  inhabitants  of  the  different  districts.  In 
other  words,  diversity  of  natural  selection  without  separation 
does  not  produce  divergent  evolution. 

"2.  We  find  many  cases  in  which  areas,  corresponding  in 
the  character  of  the  environment,  but  separated  from  each 
other  by  important  barriers,  are  the  homes  of  divergent 
forms  of  the  same  or  allied  species. 

"3.  In  cases  where  the  separation  has  been  long  continued, 
and  the  external  conditions  are  the  most  diverse  in  points 
that  involve  diversity  of  adaptation,  there  we  find  the  most 
decided  divergences  in  the  organic  forms.  That  is,  where 
separation  and  divergent  selection  have  long  acted,  the  re- 
sults are  found  to  be  the  greatest. 

"The  first  and  second  of  these  propositions  will  probably 
be  disputed  by  few,  if  by  any.  The  proof  of  the  second  is 
found  wherever  a  set  of  closely  allied  organisms  is  so  dis- 
tributed over  territory  that  each  species  and  variety  occu- 
pies its  own  narrow  district,  within  which  it  is  shut  by  bar- 
riers that  restrain  its  distribution,  while  each  species  of  the 
environing  types  is  distributed  over  the  whole  territory. 
The  distribution  of  terrestrial  molluscs  on  the  Sandwich 
Islands  presents  a  great  body  of  facts  of  this  kind." 

Finally  in  a  recent  exhaustive  discussion  of  the  subject 2T 
of  the  relation  of  isolation  to  evolution  Gulick  declares  that 
"the  whole  process  of  bionomic  evolution,  whether  progres- 
sive or  retrogressive,  whether  increasingly  ramified  and 
divergent,  or  increasingly  convergent  through  amalgama- 


OTHER  THEORIES   OF   SPECIES-FORMING.         253 

tion,  is  a  process  by  which  the  limitations  of  segregate  breed- 
ing are  either  set  up  and  established  or  cast  down  and 
obliterated." 

APPENDIX. 

1  Seebohm,  Henry,  "Physiological  Selection,"  p.  12,  1886. 

a  Romanes,  G.  J.,  "Darwin  and  After  Darwin,"  Vol.  III.  p.  I,  1897. 

8  Wagner,  Moritz,  "Die  Entstehung  der  Arten  durch  Raumliche 

References  to  Sonderung,"  1889.  This  book  is  made  up  of  the 
discussions  of  collected  papers  of  Wagner,  printed  originally  in  the 
isolation,  time  from  1868-1886,  mostly  in  the  journal  Kosmos. 

*  Wagner,  Moritz,  "Uber  den  Einfluss  der  geographischen  Isolie- 
rung  und  Kolonienbildung  auf  die  morphologischen  Veranderungen 
der  Organismen,"  July,  1870. 

6  Wagner,  Moritz,  "Uber  die  Entstehung  der  Arten  durch  Abson- 
derung,"  Kosmos,  1880, 

8  Haacke  in  his  "Grundriss  der  Entwicklungsmechanik,"  1897, 
gives,  on  pp.  335-336,  an  excellent  summary  statement  of  Wagner's 
position,  as  follows: 

"Wenn  wir  eine  Tierart  bis  an  die  Grenze  ihres  Verbreitungs- 
gebietes  verfolgen  und  diese  Grenze  uberschreiten,  so  stossen  wir 
Haacke's  sum-  gewohnlich  sehr  bald,  und  oft  schon,  ehe  wir  die 
mary  of  Wag-  Verbreitungsgrenze  der  betreffenden  Art  erreicht 
ner's  theory,  haben,  auf  eine  andere,  und  zwar  auf  eine  mit  der 
ersteren  nachstverwandte  Tierart,  die  aber  ein  anderes  Verbreitungs- 
areal  inne  hat.  Gehen  wir  auch  iiber  das  Gebiet  dieser  letzteren 
Art  hinaus,  so  konnen  wir  auf  eine  dritte,  vierte  und  fiinfte  Art 
stossen,  von  denen  jede  den  beiden  ersten  verwandt  sein  kann  und 
ein  besonderes  Verbreitungsgebiet  bewohnt.  Im  allgemeinen  kon- 
nen wir  den  Satz  aufstellen,  dass  es  keine  zwei  nachstverwandten 
Tierarten  giebt,  deren  Verbreitungsgebiete  sich  vollkommen  decken. 
Vielfach  kann  der  Fall  festgestellt  werden,  dass  die  Verbreitungsge- 
biete zweier  nachstverwandter  Tierarten  sich  teilweise  decken;  aber 
eine  vollkommene  Deckung  ist  noch  in  keinem  Fall  bei  zwei  oder 
mehr  nachstverwandten  Tierarten  festgestellt  worden.  Es  kann 
auch  vorkommen,  dass  das  Verbreitungsgebiet  der  einen  Art  voll- 
standig  innerhalb  desjenigen  der  andern  Art  liegt,  das  also,  soweit 
der  Wohnkreis  der  ersten  Art  reicht,  ein  Zusammenfallen  mit  dem 
Verbreitungsgebiet  der  zweiten  Art  stattfindet;  aber  in  solchen 
Fallen  dehnt  sich  eben  die  Heimat  der  einen  Art  uber  die  der 
zweiten  aus,  so  dass  von  Kongruenz  der  beiderseitigen  Wohnge- 
biete  nicht  die  Rede  sein  kann.  Nachtsverwandte  Tierarten  sind 


254  DARWINISM   TO-DAY. 

ketten-  oder,  besser  gesagt,  netzformig  iiber  die  Erde  verbreitet. 
Wie  die  Maschen  eines  Netzes  reihen  sich  die  Wohngebiete  der 
Arten  einer  Gattung  aneinander,  und  wenn  auch,  wie  schon  hervor- 
gehoben,  mancherlei  teilweise  Deckungen  vorkommen,  so  hat  sich 
noch  in  alien  Fallen,  wo  man  die  Grenzen  der  Verbreitungsgebiete 
nachstverwandter  Arten  festgestellt  hat,  die  Thatsache  ergeben,  dass 
keine  vollkommene  Deckung  stattfindet.  Aus  dieser  Thatsache 
konnen  wir  den  Schluss  ziehen,  dass  in  einem  und  demselben 
Gebiete,  soweit  wenigstens  alle  Individuen  unter  denselben  Ver- 
haltnissen  leben,  aus  einer  Art  nicht  zwei  oder  mehr  neue  Arten 
werden  konnen.  Wagner  meinte  zuerst,  dass  hierbei  die  Moglich- 
keit  einer  allseitigen  Kreuzung,  wie  sie  nach  ihm  innerhalb  eines 
und  desselben  Wohnkreises  einer  Art  moglich  sein  soil,  eine  grosse 
Rolle  spielt.  Er  hat  iibrigens  seine  Ansichten  im  Laufe  der  Zeit 
geandert  und  es  ist  deshalb  notwendig,  auf  die  Entwickelungs- 
geschichte  seiner  Ideen  etwas  naher  einzugehen.  Urspriinglich 
suchte  Wagner  seine  Theorie  mit  der  Darwin'schen  zu  vereinigen. 
Nach  der  letzteren  entsteht  eine  neue  Art  dadurch  aus  einer 
vorhandenen,  dass  die  Lebensbeeinflussungen  andere  werden,  und 
dass  nunmehr  diejenigen  Individuen  seitens  der  ziichtenden  Natur 
ausgewahlt  werden,  die  den  neuen  Lebensbeeinflussungen  am 
besten  entsprechen.  Wagner  nahm  nun  an,  dass  dies  zunachst  nur 
einzelne  Individuen  sein  konnen,  und  dass  nicht  bloss  sie,  sondern 
noch  eine  grosse  Anzahl  anderer  leben  bleiben,  so  dass  nicht  allein 
die  Moglichkeit,  sondern  auch  die  hohe  Wahrscheinlichkeit  gegeben 
ist,  dass  die  den  neuen  Lebensbeeinflussungen  am  besten  ent- 
sprechenden,  von  den  iibrigen  Individuen  der  betreffenden  Organis- 
menart  abweichenden  Vertreter  der  letzteren  sich  mit  denjenigen 
geschlechtlich  mischen,  die  nicht  in  zweckentsprechender  Weise 
abgeandert  sind,  wodurch  die  neuen  Errungenschaften  wieder 
verloren  gehen  sollten.  Wagner  suchte  also  den  Nachweis  zu 
fiihren,  dass  die  Darwinische  Selektionstheorie  nicht  geeignet  sei, 
eine  Ziichtung  neuer  Tier-  und  Pflanzenarten  ohne  eine  Hiilfslehre, 
die  er  in  seiner  'Migrationstheorie'  gefunden  zu  haben  glaubte, 
nachzuweisen.  Er  meinte,  dass  die  vorteilhaft  abgeanderten 
Individuen,  wenn  nicht  in  alien,  so  doch  in  manchen  Fallen  auswan- 
dern  wiirden  in  eine  Gegend,  wo  die  Art,  der  sie  angehoren,  nicht 
vertreten,  wo  also  die  Moglichkeit  einer  Kreuzung  mit  unabgean- 
derten  Individuen  ausgeschlossen  ist.  Spater  hat  Wagner  seine 
Migrationstheorie  durch  die  der  Separation  oder  der  raumlichen 
Sonderung  ersetzt,  indem  er  zugleich  die  Verquickung  seiner 
Anschauungen  mit  denen  des  Darwinismus  zuriicknahm.  Nach 
Wagners  Separationstheorie  bilden  sich  neue  Arten  dadurch,  dass 
auf  die  eine  oder  andere  Weise  etliche  Individuen  einer  Art  in  ein 


OTHER   THEORIES   OF   SPECIES-FORMING.        255 

Gebiet  gelangen,  das  vorher  nicht  von  dieser  Art  bewohnt  war. 
Die  Entstehung  neuer  Arten  erklart  sich  dann  nach  Wagner 
dadurch,  dass,  da  die  Individuen  einer  Art  ja  alle  mehr  oder 
minder  voneinander  abweichen,  die  wenigen  Griinder  der  neuen 
Art  ihre  Besonderheiten  bewahren  und  nicht  durch  Kreuzung  mit 
anderen  Individuen  wieder  einbiissen  wiirden.  Die  Anpassung 
lasst  Wagner  aber  im  Sinne  Lamarcks  zustande  kommen,  und 
neben  Einrichtungen,  die  den  Organismen  von  Nutzen  sind, 
erkennt  er  andere  an,  die  lediglich  der  Ausdruck  eigentumlicher 
Struktur  sind.  Die  klimatischen  Verhaltnisse  sind  nach  Wagner 
von  sehr  untergeordneter,  die  Verhinderung  der  Kreuzung  ist 
von  ausschlaggebender  Bedeutung.  Wagner  huldigte  ferner  der 
Anschauung,  dass  die  weisse  Farbe  der  Polar-  und  die  gelbe  der 
Wiistentiere  dadurch  zustande  gekommen  ist,  dass  entsprechend. 
gefarbte  Individuen  von  Arten,  die  andere  Gegenden  bewohnten,. 
nach  den  Polarlandern  und  den  Wiisten  auswanderten." 

7  Jordan,    D.    S.,    "The    Origin    of    Species    through    Isolation,"" 
Science,  N.   S.,  Vol.  XXII,  pp.  545-562,   1905. 

8  An  excellent  example  of  the  careful  study  of  the  relation  of  a. 
group  of  recognised  varieties,   or   sub-species  of  a   species,  to  the 

Grinnell's  stndy  climatic  differences  of  their  various  geographic 
of  geographic  ranges,  is  presented  by  Jos.  Grinnell  in  "The  Origin. 
differences  in  the  and  Distribution  of  the  Chestnut-backed  Chickadee,'* 
chickadee,  Auk>  yol  n>  pp  364.382,  1904.  I  quote  from  this 

paper  the  following : 

"The  chestnut-backed  chickadee  (Parus  rufescens)  is  a  boreal 
species  of  peculiarly  limited  distribution.  It  is  almost  exclusively 
confined  to  the  humid  Pacific  Coast  region  of  North  America, 
within  which  it  is  the  most  abundant,  and  in  many  places  the 
only  member  of  the  genus  Parus  present.  We  find  it  characteris- 
tically at  home  within  the  densest  coniferous  forests,  or  along  their 
edges,  where  there  is  much  shade  and  an  even  temperature. 

"The  range  of  the  chestnut-backed  chickadee  is  nearly  two- 
thousand  miles  long,  north  and  south,  extending  from  a  little  north 
of  Sitka,  Alaska,  to  some  forty  miles  below  Monterey,  California. 
But  its  width  is  very  narrow,  only  within  the  confines  of  Oregon 
and  Washington  exceeding  one  hundred  miles,  and  elsewhere 
usually  much  less,  save  for  one  or  two  isolated  interior  colonies 
to  be  mentioned  later. 

"The  influences  determining  this  queer-shaped  distribution  area 
may  be  safely  assumed  to  be  atmospheric  humidity,  with  associated 
floral  conditions.  For  this  habitat  coincides  quite  accurately  with 
the  narrow  coastal  belt  of  excessive  cloudy  weather  and  rainfall. 

"The   specific  character  distinguishing  Parus  rufescens  from  all 


256  DARWINISM   TO-DAY. 

other  American  chickadees  is  the  colour  of  the  back,  which  is  an 
intense  rusty-brown,  approaching  chestnut.  It  is  of  common  note 
that  the  most  evident  effects  of  similar  climatic  conditions  on  other 
animals  is  a  corresponding  intensification  of  browns,  especially 
dorsally.  We  may,  therefore,  consider  the  chestnut-backed  chicka- 
dee, as  indicated  by  its  chief  specific  character,  to  be  a  product 
exclusively  of  the  peculiar  isohumic  area  to  which  we  find  it 
confined. 

"Parus  rufescens,  from  Sitka  to  Monterey,  has  a  chestnut-coloured 
back.  And  from  Sitka  to  Point  Arena,  between  which  we  find 
the  extremest  humidity,  another  conspicuous  character  is  uniform, — 
the  colour  of  the  sides,  which  are  also  deep  rusty  brown.  But  from 
Point  Arena  south  to  San  Francisco  Bay  (Marin  District),  these 
lateral-brown  areas  suddenly  weaken  to  pale-rusty;  while  from 
San  Francisco  south  past  Monterey  (Santa  Cruz  District),  adult 
"birds  have  the  sides  pure  smoke-gray  without  a  trace  of  rusty. 

"The  species  thus  presents  geographic  variation  within  itself,  and 
three  distinguishable  forms  have  been  named,  respectively,  the  chest- 
nut-sided chickadee  (Parus  rufescens  rufescens),  the  Marin  chick- 
adee (Parus  rufescens  neglectus),  and  the  Santa  Cruz  chickadee 
(Parus  rufescens  barlowi).  But  all  three  sub-species  are  unmis- 
takably the  chestnut-backed  chickadee  (Parus  rufescens).  .  .  . 

"As  has  already  been  asserted,  Parus  rufescens  doubtless  arose 
as  a  geographical  race  of  Parus  pre-hudsonicus  [the  hypothetical 
common  ancestor  of  the  present  species,  Parus  hudsonicus,  occupy- 
ing the  interior  of  Alaska  and  British  Columbia  east  to  Labrador 
and  Nova  Scotia,  and  Parus  rufescens].  It  is  now  called  a  'species' 
because  intermediates  have  dropped  out;  in  other  words,  the 
divarication  is  now  wholly  complete  and  there  are  two  separate 
twigs.  The  area  of  intermediate  faunal  conditions  between  the 
humid  coast  belt  and  the  arid  interior  region  of  British  Columbia 
and  Alaska  is  very  narrow,  consisting,  in  places  personally 
traversed  by  me,  of  but  a  few  miles  over  a  mountain  ridge.  This 
very  narrowness  of  the  area  of  faunal  mergence  probably  accounts 
for  the  lack  of  intermediates  at  the  present  day  between  hudsonicus 
and  rufescens. 

"In  the  case  of  Parus  rufescens  and  Parus  hudsonicus,  there 
seems  to  be  now  a  narrow  hiatus  between  the  two.  At  least  I  can 
find  no  record  of  the  two  species  having  been  found  in  the  same 
locality.  The  narrowness  of  the  region  of  intermediate  faunal 
conditions  may  therefore  be  considered  as  the  reason  why  we  do 
not  find  connecting  links  between  hudsonicus  and  rufescens  at  the 
present  time.  For  the  amount  of  difference  between  these  two 
chickadees  does  not  strike  me  as  any  greater  than,  for  instance, 


OTHER   THEORIES   OF   SPECIES-FORMING.        257 

between  Melospisa  cinerea  montana  and  Melospisa  cinerea  rufina, 
between  which  there  is  continuous  distribution  and  free  interoscula- 
tion. But  we  cannot  expect  any  two  species  of  birds  or  other 
animals  to  present  the  same  degrees  of  differentiation  in  the  same 
length  of  time  or  under  the  same  conditions,  much  less  under 
different  conditions.  For  in  no  two  animals  is  the  physical  organ- 
isation, in  all  respects,  exactly  the  same. 

"In  a  given  aggregation  of  individuals  constituting  a  new  colony, 
a  certain  amount  of  time  is  necessary  for  the  set  of  environmental 
factors  to  become  operative  in  bringing  about  new  inheritable 
characters  to  a  degree  perceptible  to  us.  Then  the  inherited  effects 
of  invasion  and  cross-breeding  from  season  to  season  from  the 
adjacent  parent  centre  of  differentiation  will  be  evidenced  less  and 
less,  as  time  elapses,  as  the  distance  from  this  centre  increases. 
The  offspring  of  successively  further  removed  unions  will,  of  course, 
inherit  to  a  less  and  less  degree  the  distinctive  characters  of  the 
ancestral  stock  on  one  side  and  more  and  more  of  the  incipient 
ones  on  the  other. 

"If,  now,  the  distance  is  great  enough  to  permit  of  the  time 
required  for  adaptive  manifestations  to  become  innate,  then  we 
would  find  new  characters  making  their  appearance  distally  nearest 
the  new  centre  of  differentiation.  If  the  distance  were  too  short 
we  would  not  find  new  characters  showing  themselves  because 
they  would  be  constantly  crowded  down  by  the  influx  of  the  old. 
The  time  factor  may,  therefore,  be  reduced  by  the  intervention  of 
an  impassable  barrier.  As  an  instance,  we  find  three  (and  there 
are  probably  two  other)  insular  forms  of  the  song  sparrow  within 
a  limited  distance  among  the  Santa  Barbara  Islands,  while  through 
the  same  distance  on  the  adjacent  mainland  there  is  but  one.  Or, 
in  the  case  of  continuous  distribution,  the  time  element  may  be 
comparatively  lessened  by  the  great  distance  between  the  range 
limits,  and  it  may  be  still  further  decreased  as  these  limits  lie  in 
faunal  areas  of  more  emphatically  different  nature.  The  horned 
larks,  as  well  as  song  sparrows,  furnish  us  several  good  examples 
of  the  latter  two  rules. 

"It  is  isolation,  either  by  barriers  or  by  sufficient  distance  to 
more  than  counterbalance  inheritance  from  the  opposite  type,  that 
seems  to  me  to  be  the  absolutely  essential  condition  for  the  differ- 
entiation of  two  species,  at  least  in  birds. 

"A  strong  argument  in  support  of  this  conviction  is  that  we 
never  find  two  'sub-species'  breeding  in  the  same  faunal  area,  and 
no  two  closely  similar  species,  except  as  can  be  plainly  accounted 
for  by  the  invasion  of  one  of  them  from  a  separate  centre  of 
differentiation  in  an  adjacent  faunal  area.  An  appropriate  instance 


258  DARWINISM   TO-DAY. 

in  illustration  of  the  latter  is  the  occurrence  together,  in  the  Siski- 
you  Mountains  of  northern  California,  of  the  brown  Parus  rufescens 
of  the  wet  coastal  fauna  and  the  gray  Parus  gambeli  of  the  arid 
Sierran  fauna.  (See  Anderson  and  Grinnell,  Proc.  Ac.  Nat.  Sc,, 
Phila.,  1903,  p.  13.)  The  Siskiyou  Mountains  occupy  a  line  of 
mergence  between  the  two  faunae,  and  the  two  respectively  repre- 
sentative chickadees  have  evidently  extended  their  ranges  toward 
each  other  until  now  over  this  one  small  area  they  occupy  com- 
mon ground.  Several  parallel  cases  could  be  cited;  their  signifi- 
cance seems  obvious. 

"We  come  now  to  consider  the  origin  of  the  races  of  Parus 
rufescens.  In  a  species  of  recent  arrival  into  a  new  region  (by 
invasion  from  a  neighbouring  faunal  area),  as  it  adapts  itself  better 
and  better  to  its  new  surroundings,  granted  the  absence  of  closely- 
related  or  sharply-competing  forms,  its  numbers  will  rapidly 
increase.  This  means  that  there  will  be  increased  competition  within 
the  species  itself,  on  account  of  limited  food  supply.  The  alterna- 
tive results  are  either  starvation  for  less  vigorous  individuals 
during  recurring  seasons  of  unusual  food  scarcity,  or  dissemination 
over  a  large  area.  In  a  way  the  first  might  be  considered  as  bene- 
ficial in  the  long  run,  as  doubtless  leading  to  the  elimination  of 
the  weaker ;  such  a  process  evidently  does  take  place  to  a  greater 
or  less  degree  all  the  time,  and  is  important  for  the  betterment  of 
the  race.  But  as  a  matter  of  observation  Nature  first  resorts  to 
all  sorts  of  devices  to  ensure  the  spreading  of  individuals  over  all 
inhabitable  regions;  in  other  words,  the  extremest  intra-competi- 
tion  does  not  ensue  until  after  further  dissemination  is  impossible. 
In  birds  we  find  a  trait  evidently  developed  on  purpose  to  bring 
about  scattering  of  individuals.  This  is  the  autumnal  'mad  im- 
pulse' which  occurs  just  after  the  complete  annual  moult,  when 
both  birds-of-the-year  and  adults  are  in  the  best  physical  condition, 
and  just  before  the  stress  of  winter  food  shortage.  Even  in  the 
most  sedentary  of  birds,  in  which  no  other  trace  of  a  migratory 
instinct  is  discernible,  this  fall  season  of  unrest  is  plainly  in  evi- 
dence. I  may  suggest,  not  unreasonably,  that  autumnal  migration 
may  have  had  its  origin  in  such  a  trait  as  this,  the  return  move- 
ment in  the  spring  becoming  a  necessary  sequence.  (See  Loomis, 
Proc.  Cal.  Acad.  Sc.,  3d  series,  Zoology,  II,  Dec.,  1900,  352.)  It 
is  a  matter  of  abundant  observation  that  autumn  is  the  season  when 
we  find  the  most  unlooked-for  stragglers  far  out  of  their  normal 
range  and  when  sober,  stay-at-home  birds,  like  Pipilo  crissalis  and 
the  chickadees,  wander  far  from  the  native  haunts  where  they  so 
closely  confine  themselves  the  rest  of  the  year.  It  is  also  the  expe- 
rience of  collectors  that  the  greatest  number  of  these  stragglers 


OTHER   THEORIES   OF   SPECIES-FORMING.        259 

are  birds-of-the-year,  which  thus,  obeying  the  'mad  impulse,'  are 
led  away  from  their  birthplace  into  new  country,  where  they  may 
take  up  their  permanent  abode,  and  be  less  likely  to  compete  with 
their  parents  or  others  of  their  kind.  Then,  too,  cross-breeding 
of  distinctly  related  individuals  is  more  likely.  The  records  of 
the  Santa  Cruz  chickadee  outside  of  its  regular  breeding  range,  are 
all  of  August  to  October  dates  (Hay wards,  Gilroy,  San  Jose,  etc.). 

"Thus,  as  above  indicated,  by  the  occupancy  of  new  territory 
the  number  of  individuals  which  can  be  supported  will  corre- 
spondingly grow.  Hence  a  vigorous  colony  will  spread  out  along 
lines  of  least  resistance,  being  hindered  by  slight  faunal  changes, 
but  completely  checked  only  by  topographic  or  abrupt  climatic 
barriers.  Parus  hudsonicus  and  its  near  relative  Parus  rufescens 
are  boreal  species,  the  former  inhabiting  the  Hudsonian  Zone  and 
the  latter  a  certain  portion  of  the  Canadian.  It  seems  reasonable 
to  suppose  that  rufescens  differentiated  in  the  northern  part  of  the 
humid  coast  belt,  which  has  been  called  the  Sitkan  District.  This 
is  a  faunal  subdivision  of  the  Canadian  Zone,  and  its  northern 
part  approximates  more  closely  Hudsonian  conditions  than  south- 
erly. Granting  that  the  early  centre  of  differentiation  and  distri- 
bution of  Parus  pre-hudsonicus  rufescens  was  in  the  northern  part 
of  the  Sitkan  District,  then  the  route  of  emigration  would  be  con- 
fined to  the  narrow  southward  extension  of  that  faunal  area.  The 
habitat  of  Parus  rufescens  thus  gradually  acquired  the  long  north 
and  south  linear  appearance,  as  shown  at  this  day.  But  when  the 
pioneer  invaders  at  the  south  reached  the  vicinity  of  Point  Arena, 
they  met  with  somewhat  changed  temperature  and  consequent 
floral  conditions,  but  not  so  abrupt  as  to  constitute  a  permanent 
barrier.  Doubtless  the  progress  of  invasion  was  retarded  until 
adaptive  modifications  evolved,  which  correlatively  allowed  of 
further  invasion,  until  the  abrupt  limits  of  the  Santa  Cruz  Dis- 
trict were  reached. 

"San  Francisco  Bay  and  the  Golden  Gate  seem  to  now  form  a 
pretty  effectual  barrier  between  neglectus  on  the  north  and  barlowi 
on  the  south.  At  least,  among  the  large  number  of  skins  examined 
by  me  with  this  point  in  view,  I  can  find  none  from  one  side  that 
can  be  confidently  determined  as  being  identical  with  the  race  on 
the  other.  Neither  chickadee  has  been  found  east  of  the  bay,  nor 
anywhere  nearly  so  far  from  the  coast  belt,  except  for  one  record 
of  a  specimen  taken  in  the  fall  at  Haywards.  This  has  been  reex- 
amined  and  proved  to  be  barlowi,  as  was  to  be  expected  from  its 
contiguity.  However,  the  Golden  Gate  is  so  narrow  that  an  occa- 
sional crossing  may  take  place:  This  was  more  probable  formerly, 
when  the  redwood  timber  grew  up  to  the  Gate  on  both  sides. 


260  DARWINISM   TO-DAY. 

Heermann,  in  1853,  recorded  the  species  from  'San  Francisco.'  But 
now,  I  think,  the  bird  is  unknown  for  several  miles  on  either  side 
of  the  Gate.  Doubtless  this  barrier  accounts  in  part  for  the 
origin  of  the  distinct  form  barlozvi  within  so  short  a  distance.  .  .  . 

"As  has  become  a  generally  accepted  idea,  the  young  plumages  of 
birds,  if  different  at  all  from  those  of  the  adults,  present  a  gener- 
alised type  of  coloration ;  or,  to  express  it  in  another  way,  the 
young  more  nearly  resemble  recent  ancestral  conditions.  The 
familiar  examples  of  the  spotted,  thrush-like  plumage  of  the  young 
robin  and  the  streaked,  sparrow-like  plumage  of  young  towhees 
and  j  uncos  are  cases  in  point.  Accepting  this  phylogenetic  signifi- 
cance of  ontogeny,  we  find  the  chickadees  giving  some  interesting 
illustrations. 

"Although  the  adult  of  barlowi  has  the  sides  pure  smoke-gray, 
the  juvenal  plumage  possesses  pale-rusty  sides.  This  points 
towards  a  rusty-sided  ancestor  like  neglectus.  This  also  agrees 
perfectly  with  the  distributional  evidence,  of  origin.  The  adult  of 
neglectus  has  pale-rusty  sides;  the  young  also  has  rusty  sides,  but 
somewhat  darker  than  in  the  corresponding  age  of  barlowi,  and 
moreover  is  more  nearly  like  the  juvenal  plumage  of  rufescens. 
But  the  sides  in  adult  rufescens  are  deep  brown,  almost  chestnut, 
while  the  young  has  much  paler,  merely  dark-rusty  sides.  And 
what  is  most  significant  is  that  the  young  of  rufescens  and  hud- 
sonicus  are  much  nearer  alike  than  are  the  adults,  the  former  hav- 
ing only  very  slightly  darker  rusty  on  the  flanks.  The  young  of 
hudsonicus  in  respect  to  intensity  of  browns  almost  exactly  equal 
the  adults  of  the  same  species,  showing  that  the  present  coloration 
is  of  very  long  standing,  and  offering  further  evidence  that  hudson- 
icus is  nearest  the  common  stock  form  of  all  the  chickadees  under 
consideration.  Juvenal  characters,  resembling  ancestral  conditions, 
lag  behind  the  newer  acquired  adult  characters. 

"To  repeat:  The  young  of  barlowi  has  the  sides  paler  rusty  than 
neglectus,  neglectus  slightly  paler  than  rufescens,  but  rufescens  has 
the  sides  slightly  more  rusty  than  hudsonicus,  a  sequence  which 
accords  well  with  the  present  theories  of  origin." 

9  Kellogg,  V.  L.,  "New  Mallophaga,  I,"  Contrib.  to  Biol.  from  the 
Hopkins    Seaside    Laboratory    of   Leland    Stanford   Jr.    University, 
1806. 

10  Smith,   Jas.    P.,   "Studies    for    Students:    Geological    Study   of 
Migration  of  Marine  Invertebrates,"  Journal  of  Geology,  Vol.  Ill, 
pp.  481-495,  1895. 

11  Any  selective  breeding  or  segregation  produced  by  other  means 
than  the  separation  of  groups  of  individuals  by  actual  topographic, 
or  geographic  barriers  may  be  called  biologic  or  sexual  isolation. 


OTHER    THEORIES   OF   SPECIES-FORMING.        261 

12  Plate,  L.,  "Uber  die  Bedeutung  des  Darwin'schen  Selections- 
prinzip,"  p.  193,  1903. 

13  Hutton,  F.  W.,  "The  Place  of  Isolation  in  Or- 
Further  refer-    ganic  Evolution,"  Nat.  Science,  Vol.  XI,  pp.  240-246, 

ences  to  discus-        ~ 
sions  of  isolation,    :°97- 

14  The  not  uncommon  mating,  in  zoological  gardens, 

of  lions  and  tigers,  with  the  production  of  healthy  cubs,  is  a  case 
in  point. 

15  This  principle,  strongly  advocated  by  Romanes,  seems  first  to 
have  been  presented  by   Eimer   in   connection   with  his   theory   of 
orthogenetic  evolution.     At  least  it  enters  into  the  make-up  of  the 
Eimerian  theory.    See  account  of  Eimer's  theory  in  chapter  x  of  this 
book. 

16  Jordan,   Karl,  "Mechanische   Selection,"   1896;   see  also   Peter- 
sen,  Wilh.,  "Entstehung  der  Arten  durch  Physiologische  Isolirung," 
Biol  CentralbL,  Vol.  XXII,  pp.  468  ff .,  1902 ;  also  Vol.  XXIV,  pp. 
423-431,   467-473,    1904.     Author   describes  cases  of  marked   differ- 
ence in  reproductive  organs  (includes  primary  and  accessory  parts) 
of  closely  allied  species  of  Lepidoptera. 

17  Snodgrass,.   R.    E.,    "The    Terminal    Abdominal    Segments    of 
Female  Tipulidae,"  Jour.  N.  Y.  Ent.  Soc.,  Vol.  XI,  pp.  177-183,  1903 ; 
"The  Hypopygium  of  the  Tipulidae,"  Trans.  Amer.  Ent.  Soc.,  Vol. 
XXX,  pp.  179-235,  1904;  "The  Hypopygium  of  the  Dolichopodidae," 
Proc.  Cal.  Acad.  Sci.,  Ser.  3,  Zool.,  Vol.  Ill,  pp.  273-285,  1904. 

18  Seebohm,  H.,  "Physiological  Selection,"  1886. 

19  Wallace,  A.  R.,  "Darwinism,"  p.  180,  1891. 

20  Jordan,  Karl,  "Novitates  Zoologicse,"  pp.  426  ff.,  1896. 

21  Vernon,    H.    N.,    "Reproductive    Divergence:    An    Additional 
Factor  in  Evolution,"  Natural  Science,  Vol.  XI,  pp.  181-189,  1897. 

22  Jordan,  Karl,   "Reproductive  Divergence:  A  Factor  in  Evolu- 
tion?" Natural  Science,  Vol.  II,  pp.  317-320,  1897. 

23  Pearson,  Karl,  "Reproductive  Selection,"  Natural  Science,  Vol. 
VIII,  pp.  321-325,  1806. 

21  Romanes,  G.  J.,  "Isolation  in  Organic  Evolution,"  Monist,  Vol. 
VIII,  pp.  19-38,  1897. 

25  Gulick,  J.  T.,  "Divergent  Evolution  through  Cumulative  Segre- 
gation," Jour.  Linn.  Soc.,  Zool.,  Vol.  XX,  pp.  189-274,  1888. 

26  Gulick,  J.   T.,  Jour.  Linn.   Soc.,  Zool,  Vol.   XX,  pp.  202-211, 


27  Gulick,  J.  T.,  "Evolution,  Racial  and  Habitudinal,"  Pub.  No. 
25,  Carnegie  Institution  of  Washington,  1905.  In  this  large  paper 
are  to  be  found  references  to  all  of  the  author's  important  papers. 
Some  of  these  papers  are  reprinted  (some  completely,  some  in 
part)  in  this  monograph. 


CHAPTER  X. 

OTHER  THEORIES  OF  SPECIES-FORMING  AND 
DESCENT  (CONTINUED)  :  THEORIES  ALTER- 
NATIVE TO  SELECTION. 

WE  come  now  to  the  brief  consideration  of  three  general 
theories,  or  groups  of  theories,  which  are  offered  more  as 
alternative  or  substitutionary  theories  for  natural  selection 
than  as  auxiliary  or  supporting  theories.  These  groups  of 
theories  are  the  Lamarckian  one,  based  on  the  inheritance 
of  characters  acquired  individually  (ontogenetically)  during 
the  lifetime  of  the  organism  due  to  the  effects  of  use  and 
disuse  and  functional  stimuli;  the  general  conception  of 
orthogenesis  variously  provided  for  by  Nageli,  Eimer, 
Jaeckel  (metakinesis),  and  others,  and  finally  the  theory  of 
heterogenesis,  suggested  by  von  Kolliker,  definitely  formu- 
lated by  Korschinsky,  and  most  recently,  and  importantly, 
developed  by  de  Vries.  Few  biologists  would  hold  any  of 
these  theories  to  be  exclusively  alternative  with  natural 
selection;  de  Vries  himself  would  restrict  natural  selection 
but  little  in  its  large  and  effective  control  or  determination 
of  the  general  course  of  descent.  But  all  of  these  theories 
offer  distinctly  substitutional  methods  of  species-forming, 
and  one  of  them  includes  certainly  the  most  favoured  expla- 
nation, next  to  selection,  of  adaptation,  while  the  authors  or 
later  up-holders  of  some  of  them  actually  deny  any  con- 
structive, that  is,  adaptational,  species-forming  or  descent- 
controlling,  influence  of  natural  selection. 

The  Lamarckian  Theory. — It  is  a  great  presumption  to 
attempt  to  offer  in  so  small  a  book  as  this  any  exposition  of 
a  theory  so  long  known  and  elaborately  developed  as  the  ex- 

262 


OTHER   THEORIES   OF    SPECIES-FORMING.        263 

planation  of  adaptation  and  species-forming  known  as  La- 
marckism.     Lamarck  *  proposed  his  theory  at 
Lamarckism.  inopportune;  it  met  with  no  gen- 


eral acceptance,  but  in  later  years,  post-Darwinian  years, 
fair-minded  biologists  have  turned  back  to  the  books  and 
papers  of  this  pioneer  French  exponent  of  the  evolution 
principle  and  have  given  his  theory  the  careful  attention  and 
scrutiny  it  deserves  —  but  which  it  failed  to  get  from 
Lamarck's  contemporaries.  This  reexamination  of  the  La- 
marckian  theory  or  theories  has  given  rise  to  most  radically 
divergent  opinion  and  belief  concerning  its  worth  :  many 
biologists  account  it  of  great  value,  others  reject  it  prac- 
tically in  toto.  But  this  acceptance  or  rejection  depends 
almost  entirely  on  one's  attitude  toward  a  single  funda- 
mental part  of  it,  namely,  the  assumption  that  variations, 
modifications,  or  characteristics  acquired  during  the  life- 
time of  an  individual,  these  modifications  usually  being  due 
to  use,  disuse,  or  other  functional  stimulation  of  organs  and 
parts,  can  be  transmitted  by  this  individual  to  its  offspring. 
If  such  newly-acquired,  non-inherited  characteristics  can  be 
transmitted  in  full  and  in  detail,  or  even  approximately  so, 
from  the  parent  to  the  young,  then  Lamarckism  obviously 
offers  the  simplest  of  all  the  explanations  so  far  presented, 
of  nearly  all  active  and  of  many  passive  adaptations.  If 
such  characters  cannot  be  so  transmitted,  then  Lamarckism, 
as  plausible,  as  reasonable,  as  simple  and  effective  as  it 
seems  to  be,  is  practically  without  validity. 

Now  this  matter  of  the  inheritance  of  acquired  charac- 

ters, apparently  easily  susceptible  of  definite  proof  or  refuta- 

The  inheritance**011  ^v  observation  and  experiment,  has  been 

ofacqxiiredchar-  for  years  and  is  to-day  one  of  the  burning  prob- 

lems of  biology.     There  is  no  general  agree- 

ment about  it,  no  consensus  of  authority  even.    Just  at  pres- 

ent the  weight  of  evidence  inclines  strongly  against  such 

an  inheritance,  chiefly  because  of  Weismann's  successfully 


264  DARWINISM   TO-DAY. 

destructive  criticism  of  about  all  the  evidence  of  observa- 
tion which  has  been  offered  in  behalf  of  it.  And  yet  just  at 
the  present  time  do  biologists  recognise  more  keenly  than  ever 
the  need  and  relief  the  actuality  of  such  inheritance  would 
give  them  in  their  attempts  to  solve  the  great  problems  of 
adaptation  and  species-forming?  I  cannot  undertake  to  say 
whether  more  reputable  biologists  disbelieve  in  than  believe 
in  the  existence  of  such  inheritance,  but  it  is  obvious  that 
the  disbelievers  have  the  present  prestige  of  apparent  vic- 
tory :  tfiey  call  for  convincing  evidence  of  such  inheritance, 
and  it  is  not  produced.  On  the  other  hand,  there  are  many 
reputable,  thoughtful,  honest,  actively  working  biologists  and 
palaeontologists  (particularly  many  palaeontologists  in  pro- 
portion to  the  total  number  of  palaeontological  students)  who 
say,  although  not  loudly  and  even  a  bit  shamefacedly,  per- 
haps, that  they  must  believe  in  the  possibility  and  the  actu- 
ality of  this  inheritance;  there  is  no  getting  forward  with- 
out it. 

In  taking  up  our  brief  exposition  of  Lamarckism,  let  me 
t  say  first  that  only  in  post-Darwinian  years  has  Lamarckism 
been  put  so  strongly  in  contrast  with  Darwinism  as  it  has. 
Darwin  himself  included  part  of  Lamarckism  as  a  minor 
factor  or  influence  in  his  explanation  of  adaptation  and 
species-forming,  and  Plate,  in  the  recent  most  notable  criti- 
cal discussion  of  Darwinism,  takes  nearly  exactly  the  old 
ground  of  Darwin,  namely,  an  acceptance  of  the  inheritance, 
in  some  degree  and  under  some  conditions,  of  acquired 
characters,  and  the  consequent  possibility  of  a  certain 
amount  of  Lamarckian  orthogenesis,  i.  e.,  an  orthogenesis 
due  to  the  inheritance  of  the  results  of  use,  disuse,  and  func- 
tional stimuli.  It  is  only  neo-Darwinism  (of  Weismann, 
Wallace,  and  others)  and  neo-Lamarckism  (of  Spencer, 
Packard,  and  others)  that  are  so  radically  opposed,  so  mutu- 
ally exclusive. 

That  an  animal  in  its  lifetime,  and  especially  during  its- 


OTHER   THEORIES   OF   SPECIES-FORMING..       265- 

immature  life  can  effect  very  considerable  changes  in  some 
Theconcep-      of  its  body-parts  by  special  use  or  disuse  of 


tion  of  evolution  thege  t  Qr  that  certajn  parts  may  be  modi- 
accordmg  to  ... 

Lamarck,  fied  through  the  influence  of  external  stimuli,  is 

familiar  knowledge.  Let  one  recall  the  increase  of  the 
blacksmith's  biceps  and  inversely  the  degeneration  of  un- 
used muscles,  and  the  thickening  or  callousing  of  palms  or 
other  parts  of  the  skin  exposed  to  repeated  rough  contact- 
Bones  have  ridges  developed  on  them  by  repeated  muscle- 
pulls,  the  hands  and  eyes  can  be  trained  to  special  functional 
skill  which  involves  important  although  perhaps  slight  physi- 
cal changes,  the  heart  and  lungs  can  be  enlarged  by  special 
use  ;  in  short,  almost  any  of  the  organs  of  the  body,  which 
are  actively  used,  can  be  modified  either  by  unusual  or  extra 
use,  or  by  unusual  lack  of  use.  Now  this  use  is,  in  Nature, 
almost  always  of  the  character  of  a  better  aiding  in  success- 
ful living  ;  that  is,  it  is  adaptive  use.  Animals  often  chased 
by  enemies  become  fleeter  by  practice;  animals  that  must 
dig  for  roots  or  climb  trees  for  leaves  and  fruits,  or  dive  for 
fishes,  or  leap  over  obstacles,  come  by  repeated  digging,  climb- 
ing, diving,  or  leaping  to  do  these  things  better  ;  the  muscles 
and  tendons  and  bones  work  together  better  and  better,. 
become  physically  modified  in  accordance  with  these  endeav- 
ours. If  such  betterment  of  organs  and  their  functions 
acquired  by  individuals  could  be  inherited  by  their  young, 
it  is  obvious  that  general  adaptations  of  this  sort  could  be 
rapidly  developed  in  the  course  of  generations,  and  new 
species,  new,  that  is,  because  of  the  adaptive  changes  thus 
effected,  be  formed.  This  is  the  essential  thought  in 
Lamarck's  theory  of  the  method  of  adaptation  and  species- 
forming.  In  almost  all  criticisms  of  Lamarckism  one  reads 
much  contemptuous  reference  to  the  expected  results  of  the 
organism's  "willing"  to  vary  or  change  in  this  or  that  direc- 
tion. As  a  matter  of  fact  the  critics  of  Lamarckism  give 
that  rather  absurd  feature  of  alleged  Lamarckism  much 


266  DARWINISM   TO-DAY. 

more  conspicuousness  than  Lamarck  did.  He  did,  indeed, 
make  some  reference  to  the  possible  volitional  effort  of  the 
organism  to  change  along  certain  desirable  lines,  but  it  is 
evident  that  Lamarck  had  more  in  mind  the  animal's  desires 
and  needs  to  stretch  up  higher  for  leaves  or  to  dig  better  or 
run  faster,  leading  to  actual  attempts  to  do  these  things,  than 
to  any  expected  results  of  mere  mental  wishing  or  willing. 
The  essential  principle  of  Lamarckism  is  an  orthogenetic 
evolutionary  progress  toward  better  and  finer  adaptation  and 
adjustment  resulting  from  the  inherited  effects  of  actual  use, 
disuse,  and  functional  stimulation  of  parts.  It  is  a  great 
thought  and  a  clear  one,  and  only  needs  the  proof  of  the 
actuality  of  the  inheritance  of  individually  acquired  char- 
acters to  make  it  one  of  the  principal  causal  explanations 
of  adaptation  and  species  change. 

However,  it  is  exactly  this  proof  that  is  wanting.    At  any 
rate,  proof  of  the  character  and  extent  necessary  to  con- 
vince all  or  even  a  majority  of  biologists   is 

Weismann's  J         ' 

successful  attack  wanting.  The  examples  or  cases  brought  for- 
onLamarckism,  ward  by  Lamarddans  of  the  alleged  inheritance 
of  mutilations,  of  the  results  of  disease,  and  of  use  and 
disuse,  are  not  convincing.  It  is  one  of  Weismann's  posi- 
tive contributions  to  biology  to  have  analysed  case  after 
case  of  alleged  inheritance  of  acquired  characters,  and  shown 
its  falseness  or  at  least  uncertainty.  Many  of  these  cases 
he  has  been  able  to  explain  as  a  result  of  selection;  others 
remain  inexplicable;  a  few,2  only,  are  insisted  on  by  the 
Lamarckian  champions  as  indisputable  examples  of  such 
inheritance.  But  this  very  paucity  of  so-called  proved 
cases,  where  there  should  be  thousands  of  obvious  ex- 
amples if  the  principle  were  really  sound,  is  argument  against 
Lamarckism. 

Our  knowledge,  too,  of  the  mechanism  of  heredity  makes 
strongly  against  the  theory  of  the  inheritance  of  acquired 
characters.  Another  of  Weismann's  positive  contributions 


OTHER   THEORIES   OF   SPECIES-FORMING.        267 

to  biology  is  his  generally  sound  distinction  between  the 
germ-plasm  and  the  soma-plasm  and  parts  of  the  many- 
celled  body.  At  maturity  the  animal  body  is  composed  of  a 
small  mass  of  germ-plasm  (germ-cells)  situated  in  the 
ovaries  or  testes,  and  a  great  mass  of  somatic  tissues  and 
organs,  all  the  rest  of  the  body,  in  fact.  Now  what  is  the 
condition  that  exists  in  the  body  after  a  somatic  part  is 
modified  by  use  or  disuse  or  by  other  functional  stimulus,  as 
when  a  muscle  is  enlarged  by  exercise,  the  sole  of  the  foot 
calloused  by  going  barefoot,  an  ear  more  finely  attuned  by 
training?  We  have  a  definite  physical  change  in  a  definite 
organ,  but  is  the  germ-plasm  in  any  way  changed  or 
affected  by  this  superficial  or  specific  somatic  modification, 
or  if  changed  is  it  changed  so  that  it  will  reproduce  in  its 
future  development  a  similar  change  in  the  same  organ  of 
the  future  new  individual  ?  What  possible  mechanism  have 
we  in  the  body  to  produce  or  insure  such  an  effect  on  the 
germ-plasm?  The  answer  is  obvious  and  flat;  we  certainly 
know  of  no  such  mechanism;  in  fact  what  we  do  know  of 
the  relation  of  the  germ-cells  to  the  rest  of  the  body  makes 
any  satisfactory  conception  of  such  a  mechanism  as  yet 
impossible. 

Not  that  certain  external  conditions  may  not  directly 
affect  the  germ-cells,  imbedded  and  concealed  as  they  are 

in  the  body.     Varying  conditions  of  tempera- 
Difficulties  in  J  J    & 
-the  way  of         ture,*  of  humidity,  and  of  magnetism,  perhaps, 

SitaL^f  certain]y  anything  influencing  the  food  supply 
acquired  char-  and  nutrition,  can  influence  the  germ-cells  at 
the  same  time  as  it  affects  all  the  rest  of  the 
body.  But  will  this  influence  photograph  on  these  un- 
differentiated  cells  the  same  picture  that  it  impresses  on  the 

*  While  temperature  may  be  looked  on  as  an  extrinsic  influence 
affecting  germ-cells  as  well  as  all  other  parts  of  the  body,  it  must  be 
kept  in  mind  that  warm-blooded  animals  (birds  and  mammals) 
regulate  the  inner  temperature  of  the  body.  So  changes  in  external 
temperature  would  but  slightly,  or  not  at  all,  affect  the  germ-cells. 


368  DARWINISM   TO-DAY. 

affected  somatic  parts.  A  high  temperature  or  a  moist  at- 
mosphere may  modify  the  colour  of  the  skin,  change  the  pat- 
tern of  the  body  superficies,  but  will  overheated  germ-cells 
produce  new  individuals  showing  the  same  changes  of  skin 
colour  and  pattern  if  the  same  conditions  of  environment  of 
the  soma  are  not  repeated?  How  much  less  conceivable, 
then,  is  the  influencing  of  the  germ-cells  so  as  to  compel 
them  to  reproduce  on  daughter  body-parts  specific  effects 
produced  on  special  parental  body-parts  by  such  specific  and 
localised  influences  as  vigorous  use  of  an  arm,  disuse  of  a 
leg  muscle,  repeated  contact  of  the  palm  of  the  hand  with 
hard  bodies.  Indeed,  this  lack  of  means  of  relating  the 
germ-plasm  to  the  soma,  the  rest  of  the  body,  has  stood 
much  in  the  way  of  any  satisfactory  conception  of  the  phe- 
nomena of  heredity,  that  is,  the  reproduction  by  the  germ- 
cells  of  new  individuals  resembling  the  parental,  and  kas 
led  to  constant  and  thoughtful  attention  and  speculation  ever 
since  the  time  of  Darwin;  indeed,  from  long  before  Dar- 
win's time. 

One  of  the  most  favoured  ways  of  attempting  to  explain 
how  the  germ-cells  can  represent  in  their  make-up,  and 
possess  the  capacity  to  develop  into,  the  whole  complex  body, 
has  been  to  conceive  of  the  giving  off  of  small  representa- 
tive particles  from  all  the  cells  of  the  body  which  should  be 
carried  by  the  blood  to  the  germ-plasm  and  deposited  in  the 
germ-cells.  The  germ-cells  in  their  development  would 
then,  by  virtue  of  this  manifold  representation,  be  able  to 
expand  into  the  whole  body  during  a  shorter  or  longer 
course  of  development  and  growth.  This  notion  of  the  com- 
position of  the  germ-plasm  of  micromeres  collected  from  all 
the  somatic  cells,  is  the  conception  at  the  basis  of  Buffon's 
theory  of  "organic  molecules,"  of  Spencer's  "physiological 
units,"  Maggi's  "plastidules,"  Altmann's  "bioblasts,"  Wies- 
ner's  "plasomes,"  Darwin's  "gemmules,"  Galton's  "stirps," 
Nageli's  "micellae,"  Weismann's  "biophors  and  determi- 


OTHER   THEORIES   OF   SPECIES-FORMING.        269 

nants,"  and  of  numerous  other  micromeric  theories.8  But 
the  facts  of  budding,  especially  as  exemplified  in  plants, 
and  of  regeneration  among  animals,  both  of  these  kinds  of 
phenomena  seeming  to  show  that  germ-plasm  is  not  neces- 
sarily limited  to  the  germ-cells,  strictly  so-called,  have  pre- 
vented the  acceptance  of  a  too  rigorous  interpretation  of 
Weismann's  distinction  between  the  germ-plasm  and  the 
soma,  and  have  led  to  some  theories  of  germ-plasm  make-up 
and  disposition  differing  from  the  ones  proposing  a  rigid 
restriction  of  germ-plasm  to  the  germ-cells.  The  facts  that 
in  many  plants  any  part,  as  a  bit  of  a  twig,  say,  if  cut  off,  can 
reproduce  the  whole  plant  just  as  effectively  as  a  seed 
(germ-cell)  can,  and  that  many  animals  can  reproduce  con- 
siderable and  complex  parts,  if  lost  by  accident  or  self- 
mutilation,  show  that  there  often  resides  in  somatic  cells  of 
much  specialisation  the  capacity  to  reproduce  not  only  cells 
of  their  own  kind  but  others  of  much  variety  and  different 
specialisation.  So  some  biologists  believe  that  there  is  either 
a  net-work  of  primitive  germ-plasm  extending  throughout 
the  soma  cells  (Nageli's  idioplasm  theory  for  example),  or 
that  each  somatic  cell  (at  least  those  with  the  capacity  of 
regeneration  or  reproduction  by  budding,  cuttings,  etc.)  con- 
tains a  little  primitive  germ-plasm  stuff  besides  its  own 
soma-plasm.  And  some  authors  have  seen  in  such  theories 
of  a  widely  diffused  germ-plasm  a  mechanism  for  the  trans- 
mission from  the  soma  to  the  central  germ-cells  of  the 
effects  of  use,  disuse,  and  functional  stimuli  derived  from 
external  sources.  But  does  even  this  conception  of  a  diffuse 
and  connected  germ-plasm,  after  all,  clear  up  in  any  way 
our  difficulty?  It  makes  it  easier  to  see  how  germ-plasm 
may  be  affected  by  external  and  superficial  influences,  but 
does  it  explain  in  any  degree  how  these  effects  can  be  car- 
ried to  the  germ-cells  and  so  stamped  on  them  as  to  compel 
them  to  reproduce  photographically  in  their  later  develop- 
ment into  new  individuals,  the  specific  effects  that  use,  dis- 


270  DARWINISM  TO-DAY. 

use,  and  external  stimuli  may  have  had  on  specific  soma 
parts  of  the  parent? 

Indeed,  Haacke  *  well  points  out  that  many  or  most  cases 
of  apparently  direct  working  of  extrinsic  influences  on  the 
body  are  really  indirect,  in  that  these  influences 
^°  not  actua^y  directly  modify  the  structure,  as 
a  blacksmith's  hammer  modifies  the  shape  of  a 
piece  of  red-hot  iron,  or  a  seal  shapes  the  drop  of  melted 
wax,  but  that  they  do  it  indirectly  as  stimuli  inducing  chemi- 
cal processes,  nervous  impulses,  etc.  The  adaptive  re- 
arrangement of  spongy  tissue  in  broken  and  poorly  reset 
long  bones,  apparently  a  direct  reaction,  is  really  only  in- 
direct, occurring  through  complex  chemical  processes,  i.  e., 
the  bringing  of  special  bone-forming  materials  to  certain 
places,  etc.  The  outer  influences  are  all  stimuli,  not  actual 
sufficient  causes  or  manipulations. 

Haacke  makes  a  proposal  of  much  ingenuity,  after  a  keen 
and  suggestive  discussion  of  the  inheritance  of  acquired 
characters  problem,  to  explain  how  such  an  inheritance  may 
be  effected.  It  is  based  on  the  fact  that  no  characters  are 
directly  acquired ;  that  is,  that  any  change  is  only  the  result 
of  some  external  stimulus  and  not  of  a  directly  and  imme- 
diately moulding  cause,  and  that,  therefore,  in  any  phenom- 
enon of  stimulus  and  effect  much  more  of  the  body  substance 
than  that  composing  the  exact  part  or  region  modified  is 
influenced.  From  this  Haacke  sees  the  possibility,  even  the 
necessity,  of  a  modification  of  the  whole  constitution,  includ- 
ing the  germ-plasm  (or  perhaps  the  germ-plasm  is  modified 
as  a  result  of  the  modification  of  the  whole  constitution  or 
body  in  which  the  germ-plasm  is  being  developed  and 
formed).  Thus  every  acquirement  of  a  new  character  or 
change  in  an  old  one  must  or  may  affect  the  germ-plasm. 
With  regard  to  passive  organs  such  as  the  chitin  skeletal 
parts  of  insects  and  crabs,  Haacke  points  out  that  they  are 
only  the  product  of  active  organs,  i.  e.,  the  secreting  skin- 


OTHER   THEORIES   OF   SPECIES-FORMING.        271 

cells,  etc.  Use  and  disuse  are  equivalent  simply  to  much  or 
little  metabolism,  and  metabolism  is  as  necessary  to  produce 
passive  organs  or  to  change  them,  as  use  is  to  make  muscles 
larger. 

However,  despite  the  successful  destructive  criticism  by 
Weismann  and  the  neo-Darwinians  of  the  alleged  cases  of 
Many  natural-  tne  inheritance  of  acquired  characters  adduced 
ists  believe  in  by  the  Lamarckians,  and  in  spite  of  our  lack  of 
of  acquired  knowledge,  and  indeed,  difficulty  of  conception 
characters,  of  anv  mechanism  in  the  body  capable  of  im- 
pressing on  the  germ-plasm  the  effects  of  use,  disuse,  and 
external  stimuli  in  such  a  way  as  to  compel  a  photographic 
reproduction  in  the  young  of  these  effects  as  manifest  in 
the  soma  of  the  parent,  numerous  biologists  do  not  hesitate 
to  avow  their  conviction  of  the  actuality  of  such  inheritance. 
Now  these  biologists  must  have  some  basis  of  observation  or 
scientific  fact  for  their  belief.  What  is  this  basis  ?  They  rest 
their  belief  largely  upon  a  kind  of  proof  by  indirection,  a 
certain  necessity  of  consequence  of  other  facts,  and  a  logical 
argument  by  elimination.  The  actual  observed  status  of 
animal  life  to-day  and,  as  revealed  by  fossils,  in  past  ages, 
which  is  that  of  the  existence  of  certain  lines  of  descent  or 
evolution  obviously  following  lines  of  modification  based 
on  use  and  disuse;  the  inadequacy  of  natural  selection  to 
explain  the  cumulation  of  adaptive  modification  until  such 
modification  shall  have  reached  a  life-and-death  determin- 
ing selective  value ;  the  apparent  impossibility  of  explaining 
the  continued  degeneration  of  vestigial  organs  by  natural 
selection ;  the  great  difficulty  of  explaining  correlative  or 
coadaptive  modifications  by  selection  alone;  the  possibility 
that  our  lack  of  knowledge  of  a  mechanism  for  ensuring  the 
hereditary  transmission  of  acquired  characters  may  be  over- 
come with  further  knowledge  of  the  ultimate  structure  and 
capacity  of  the  germ-plasm;  the  great  reasonableness  and 
logical  plausibility  of  the  whole  Lamarckian  conception; 


•2J2  DARWINISM   TO-DAY. 

these  and  other  similarly  not  wholly  convincing  reasons  are 
the  sort  of  not  very  admirable  scientific  evidence  that  the 
believers  in  Lamarckism  have  to  stand  on.  Two  groups  of 
scientific  men  are  especially  well  represented  among  the 
Lamarckians :  namely,  palaeontologists  and  pathologists. 
(Not  all  palaeontologists  and  pathologists  believe  in  the 
inheritance  of  acquired  characters.)  Both  of  these  groups 
are  familiar  with  facts  that  are  unfamiliar  to  biologists  gen- 
erally. And  to  my  mind  it  is  important  that  biologists  should 
recognise  the  fact  that  familiarity  with  the  facts  of  histor- 
ical geology  on  the  one  hand  and  with  teratogenesis  and 
human  disease  on  the  other,  seems  to  lead  to  a  belief  in 
Lamarckism.*  It  should  lead  the  general  biologist  to  be 
less  positive  in  his  sureness  of  the  invalidity  of  Lamarckism. 
But  even  were  the  inheritance  of  acquired  characters  now 
an  established  fact,  or  if  it  should  come  to  be  one,  it  must 
Lamarckism  be  kept  in  mind  that  Lamarckism  could  be  sub- 

pSulluTapta-  stituted  only  Partly  for  Darwinism.  There  are 
tions,  many  adaptations  and  much  species-forming 

that  Lamarckism  might  explain,  but  also  there  are  hosts  of 
adaptations  that  Lamarckism  cannot  explain.  Plate,5  who 
defends  natural  selection  but  accepts  some  part  of  Lamarck- 
ism, has  pointed  this  out  clearly.  He  asks  how  the  so-called 
""passive  adaptations"  could  be  explained  by  Lamarckism. 
"The  salivary  glands  of  a  non-poisonous  snake  could  pro- 
duce ever  so  much  saliva,  but  it  would  not  become  poison- 
ous by  this,  just  as  little  as  simple  teeth  could  change  by 
use  to  grooved  teeth  and  these  to  tubular  ones.  The  tusks 
of  Babirussa  could  not  be  led  to  grow  through  the  skin  of 
the  cheeks  through  use,  for  they  would  have  to  be  actually 

*  A  scientific  man  representing  another  phase  of  biologic  activity, 
•and  a  man  who  has  enjoyed  an  extraordinary  opportunity  for  the 
observation  and  testing  of  modes  of  inheritance,  also  believes 
strongly  in  Lamarckism.  This  is  Luther  Burbank,  the  famous  Cali- 
fornia plant-breeder.  For  some  account 8  of  the  scientific  aspects  of 
Burbank's  work,  see  the  appendix  of  this  chapter. 


OTHER   THEORIES   OF   SPECIES-FORMING.        273 

covered  by  the  flesh  for  awhile  in  this  process,  and  during 
this  time  be  incapable  of  use.  With  Fierasfer,  the  fish  that 
lives  in  sea-cucumbers  (Holothurians),  the  anus  lies  far  for- 
ward in  the  throat  so  that  the  fish  has  only  to  thrust  its  head 
through  the  anus  of  the  sea-cucumber  in  order  to  void  its 
faeces.  How  can  use  of  the  intestine  or  its  peristaltic  move- 
ment have  produced  such  a  remarkable  change  in  position 
of  the  anus  ?"  Plate  7  offers  other  similar  examples  of  adap- 
tations inexplicable  by  Lamarckism,  and  justly  says  that 
hundreds  of  others  could  be  adduced.  He  presents  suc- 
cinctly the  possibilities  of  Lamarckism,  the  inheritance  of 
acquired  characters  being  granted,  as  follows  : 
Lamarckism  could  explain 

1 i )  many   indifferent   characters :   example,   changes   of 
temperature   produce   proportional   changes    in   the 
colour-pattern  of  butterflies'  wings ; 

(2)  many  simple  adaptations  of  active  organs :  example, 
a  muscle  becomes  stronger  through  use,  and  creates 
a  crest  on  a  bone  through  pulls ; 

(3)  some  simple  adaptations  of  passive  organs  (so-called 
direct    adaptations)  :   example,   in   the    whales,    the 
water  might  directly  affect  the  skin  and  sub-cutane- 
ous tissue  and  thus  produce  the  loss  of  hair  and  the 
layer  of  fat. 

Lamarckism  could  not  explain 

(1)  many  characters  of  active  adaptation,  even  though 
of  simple  kind :  example,  the  penetrating  of  the  lung- 
sacs  of  birds  through  hair-fine  holes  into  all  the 
bones ; 

(2)  many  complicated  adaptations  of  active  organs :  ex- 
amples, light-making  organs,  eyes,  smelling-organs, 
auditory  organs ; 

(3)  all  complicated  passive  adaptations :  example,  mim- 
icry. 

Even  if  we  are  ready  to.  admit  the  possibility  or  actuality 


274  DARWINISM   TO-DAY. 

of  the  inheritance  of  acquired  characters  in  some  degree  or 
under  certain  conditions — and  this  partial  acceptance  has 
always  seemed  to  me  no  more  justified  than  the  flat  accept- 
ance of  the  principle  in  its  entirety;  it  has  seemed  a  weak 
sort  of  attempt  at  compromise  with  no  real  basis  in  reason 
and  effecting  no  advantage  in  clearing  up  the  problem — 
there  can  be  no  acceptance  of  the  all-sufficiency  of  Lamarck- 
ism  as  an  explanation  of  adaptation,  species-forming,  and 
descent,  any  more  than  there  can  be  such  an  acceptance  of 
the  all-sufficiency  of  natural  selection.  Adaptation  and  spe- 
cies-forming are  not,  to  my  mind,  one  and  the  same  problem  : 
adaptation  can  and  does  lead  to  species-forming,  but  species 
are  formed  that  are  not  the  results  of  adaptive  modifica- 
tion ;  whose  specific  characteristics  are  indifferent ;  that  are, 
in  a  word,  non-adaptive  species.  De  Vries's  new  species  of 
evening  primroses  have  a  cause  not  associated  with  adapta- 
tion. Now  Lamarckism  certainly  cannot  explain  non- 
adaptive  species  any  better  than  selection  can.  Both  selec- 
tion and  the  inheritance  of  the  effects  of  use,  disuse,  and 
external  stimuli  are  primarily  explanations  of  adaptations 
and  of  adaptive  species-forming.  Lamarckism  is,  perhaps,, 
through  its  inclusion  of  the  perpetuation  of  the  direct  influ- 
ence of  external  stimuli,  in  better  condition  to  explain  non- 
adaptive  species,  but  both  of  these  genius-offered  explana- 
tions of  organic  evolution  need  the  aid  of  another  or  other 
factors :  the  unknown  factors  of  evolution,  to  speak  with 
Osborn. 

Orthogenesis. — One   of   the   principal   criticisms   of   the 
natural  selection  theory  is  that  of  the  impossibility  of  ex- 
plaining- the  beginnings  of  advantageous  modi- 
Apparent  evi-    J 

dence  for  ortho-  fication  and  the  beginnings  of  new  organs,  by 
genetic  evolution,  the  seiection  of  fluctuating  individual  variation, 
and  of  explaining  the  apparent  cases  of  the  existence  of 
determinate  variation  and  the  admitted  cases  of  forthright 
development  along  fixed  lines  not  apparently  advantageous,, 


OTHER   THEORIES   OF    SPECIES-FORMING.        275 

and  finally  of  explaining  the  definite  cases  of  ultra-develop- 
ment of  parts  and  species  beyond  the  point  of  advantage  even 
to  such  unfavourable  degrees  as  lead  to  death  and  extinction. 
Palaeontology  8  reveals  to  us  the  one-time  existence  of  ani- 
mals, of  groups  of  animals,  and  of  lines  of  descent,  which 
have  had  characteristics  which  led  to  extinction.  The  un- 
wieldiness  of  the  giant  Cretaceous  reptiles,  the  fixed  habit 
of  life  of  the  crinoids,  the  coiling  of  the  ammonites  and 
nautili,  the  gigantic  antlers  of  the  Irish  stag — all  these  are 
examples  of  development  along  disadvantageous  lines,  or  to 
disadvantageous  degrees.  The  statistical  studies  of  varia- 
tion have  made  known  numerous  cases  9  where  the  slight,  as 
yet  non-significant  (in  a  life-and-death  struggle)  variation 
in  pattern  of  insects,  in  dimension  of  parts,  in  relative  pro- 
portions of  superficial  non-active  structures,  are  not  for- 
tuitous, that  is,  do  not  occur  scattered  evenly  about  a  mean 
or  mode  according  to  the  law  of  error,  but  show  an  obvious 
and  consistent  tendency  to  occur  along  certain  lines,  to 
accumulate  in  certain  directions.  Many  biologists  see  in 
variation  and  in  species-forming  certain  determinate  char- 
acteristics exhibited  by,  or  lines  or  paths  being  followed  by 
all  or  most  of  the  individuals  of  successive  generations ;  and 
see  in  descent  certain  phenomena  of  forthright  progressive 
movement  which  they  find  selection  based  on  utility  unable 
to  explain.  Various  theories  to  account  for  this  apparent 
orthogenetic,  but  not  ortho-selective,  development  have 
therefore  been  proposed  by  biologists,  most  of  which 
theories  and  most  of  which  biologists  are  to  be  looked  on  as 
antagonistic  to  the  selection  theory.  For  if  a  theory  of  ortho- 
genesis is  sufficient  to  explain  those  lines  of  variation  and 
development  not  explicable  by  selection,  it  usually  seems  to 
its  maker  to  be  sufficient  to  explain  other  lines  of  evolution. 
It  may  very  likely  occur  to  some  that  in  speaking  of  ortho- 
genetic  development  as  contrasted  with  descent  governed  by 
selection  we  are  making  a  distinction  without  a  difference, 


276  DARWINISM   TO-DAY. 

in  that   it  is   obvious   that   selection   also   produces   ortho- 
genetic   evolution,   that   is,   evolution   along   definite   lines ; 
that  in  fact  it  can  produce  no  other  kind  of 
Orthogenesis     evolution.    To  attribute  orthogenetic  results  to 

contrasted  with  .       ,  .    ,  ,          .  . 

orthoselection.  natural  selection  is  quite  right,  and  some  one  has 
proposed  the  name  orthoselection  to  distinguish 
orthogenetic  evolution  as  produced  by  selection  from  such 
results  produced  independently,  or  at  least  partly  inde- 
pendently of  selection,  that  is  produced  in  accordance  with 
any  one  or  more  of  the  so-called  theories  of  orthogenesis. 
All  this  latter  kind  of  orthogenesis  is  distinguished  from 
orthoselection  in  that  it  presumes  all  or  most  of  the  indi- 
viduals of  successive  generations  to  be  modified,  to  vary, 
that  is,  in  a  similar  manner  as  a  result  of  factors,  intrinsic 
or  extrinsic,  producing  determinate  variation.  This  is 
plainly  different  from  orthoselection,  in  which  definite  lines 
of  development  are  produced  by  the  eradication,  through  the 
rigour  of  selective  struggle,  of  all  other  lines.  Variation 
may  be  wholly  fortuitous,  miscellaneous,  indeterminate ;  but 
selection  permits  only  certain  kinds  of  variation"  to  persist, 
to  accumulate.  In  true  orthogenesis  the  variation,  and 
hence  the  lines  of  modification,  are  predetermined.  It  seems 
obvious,  however,  to  any  believer  in  natural  selection  that 
sooner  or  later  the  fate  of  these  lines  of  development  will 
come  into  the  hands  of  selection.  And  most  orthogenesists 
do  indeed  admit  this.  But  it  is  precisely  in  the  making  of 
a  start  in  modification  that  orthogenesis  fills  a  long-felt 
want,  and  if  capable  of  proof,  should  be  gladly  received  by 
Darwinians  as  an  important  auxiliary  theory  in  the  ex- 
planation of  modification,  species-forming,  and  descent. 

The  first  of  these  theories  of  orthogenesis  has  just  been 
explained,  for  Lamarckism  may  be  looked  on  as  an  expla- 
nation of  orthogenetic  evolution  based  on  the  perpetuation 
and  accumulation  of  the  effects  of  use,  disuse,  and  the 
direct  effects  of  functional  stimuli.  Roux's  battle  of  the 


OTHER   THEORIES   OF   SPECIES-FORMING.       277 

parts  theory,  and  Weismann's  theory  of  germinal  selection 
are  also  in  a  way  theories  of  orthogenesis :  they  explain  how 
variations  begin  and  continue  along  fixed  lines,  but  they 
both  soon  surrender  control  of  descent  to  natural  selection. 
There  are,  however,  two  or  three  theories  of 

Different  types  orthogenesis  which  have  been  developed  by 
olttgetesif  their  proposers  to  the  Degree  where  they  are 
boldly  offered  as  substitutes  for  natural  selec- 
tion. Two  especially  notable  theories  of  this  character  are 
those  proposed  and  defended  respectively  by  Nageli  and  by 
Eimer.  These  two  are  not  only  the  most  notable  and  most 
completely  elaborated  of  orthogenetic  theories  but  they 
represent  two  radically  different  points  of  view  among  the 
orthogenesists  themselves,  in  that  Nageli  found  his  ortho- 
genesis-producing factor  or  cause  in  a  somewhat  mystical 
vitalistic  inner  force,  or  so-called  Vervollkomnungsprinzip, 
in  the  organism,  while  Eimer  finds  orthogenesis  produced 
and  controlled  by  the  directly  working  external  factors  of 
climate,  food  supply,  and  environment  generally.  Similar 
conceptions  or  beliefs  regarding  the  direct  and  accumulating 
effect  of  environmental  factors  have  been  presented  by  Dar- 
win, Haeckel,  Cope,  Henslow,  Emery,  Piepers,  Lloyd 
Morgan,  and  numerous  others.  In  fact  probably  a  majority 
of  biologists  entertain  a  conviction, — often  not  clearly  de- 
fined and  generally  unaccompanied  by  any  satisfactory  con- 
ception of  a  mechanism  for  achieving  what  they  believe 
to  exist, — of  the  actuality  of  an  influence  on  organic  modifi- 
cation and  descent  directly  exerted  by  those  various  external 
factors  or  conditions  of  organic  life  which  we  call,  collec- 
tively, environment. 

Nageli's  10  theory  of  orthogenesis  depends  upon  the  as- 
sumption of  his  so-called  principle  of  progressive  develop- 

Nageli's  theory  ment  (  Vervollkomnungsprinsip),  a  something 
of  orthogenesis,  inherent  in  the  organic  world  which  makes 
each  organism  in  itself  a  force  or  factor  making  towards 


278  DARWINISM   TO-DAY. 

specialisation,  adaptation,  that  is,  towards  progressive  evo- 
lution. Other  authors  who  accept  such  a  theory  of  an  inher- 
ent driving  force  in  organisms  speak  of  this  factor  variously 
as  an  "inner  directive  force,"  an  "inner  law  of  development," 
or  an  "intrinsic  tendency  towards  progress,"  etc.  Nageli 
believes  that  animals  and  plants  would  have  developed  about 
as  they  have  even  had  no  struggle  for  existence  taken  place 
and  the  climatic  and  geologic  conditions  and  changes  been 
quite  different  from  what  they  actually  have  been.  Kor- 
schinsky  1X  says:  "In  order  to  explain  the  origin  of  higher 
forms  out  of  lower  it  is  necessary  to  assume  in  the  organism 
a  special  tendency  towards  progress."  That  is,  to  the  be- 
lievers in  this  kind  of  a  theory  of  orthogenesis  organic 
evolution  has  been  and  is  now  ruled  by  unknown  inner 
forces  inherent  in  organisms,  and  has  been  independent  of 
the  influence  of  the  outer  world.  The  lines  of  evolution  are 
immanent,  unchangeable,  and  ever  slowly  stretch  toward 
some  ideal  goal.  It  is  needless  to  say  that  but  few  biologists 
confess  to  such  a  belief.  However  much  in  the  dark  we 
may  be  regarding  the  whole  great  secret  of  bionomics,  how- 
ever partial  and  fragmentary  our  knowledge  of  the  processes 
and  mechanism  of  evolution,  such  an  assumption  of  a  mystic, 
essentially  teleologic  force  wholly  independent  of  and 
dominating  all  the  physico-chemical  forces  and  influences 
that  we  do  know  and  the  reactions  and  behaviour  of  living 
matter  to  these  influences  which  we  are  beginning  to 
recognise  and  understand  with  some  clearness  and  fulness — 
such  a  surrender  of  all  our  hardly  won  actual  scientific 
knowledge  in  favour  of  an  unknown,  unproved,  mystic  vital 
force  we  are  not  prepared  to  make.  As  Plate  well  says,  such 
a  theory  of  orthogenesis  12  is  opposed,  in  sharpest  contrast, 
to  the  very  spirit  of  science. 

On  the  contrary,  the  theories  of  orthogenesis  of  the 
general  type  exemplified  by  Rimer's  13  are  directly  in  line 
with  the  spirit  of  modern  biological  methods  and  investiga- 


OTHER   THEORIES   OF   SPECIES-FORMING.        279 

tions ;  they   rest  on  the  assumption  that  physico-chemical 

factors  produce  direct  effects  on  the  plastic  organism,  and 

that  such  effects,  repeated  and  intensified,  re- 

Another  type 

of  orthogenetic     suit  in  a  certain  degree  of  modification  or  con- 
theory,  troi  Of   variation   and  evolution.    To  be   sure, 

there  is  not  yet  proposed  a  very  satisfactory  mechanism 
for  conveying  the  environmental  influence  to,  and  trans- 
lating it  into  definite  effect  on  the  course  of  development, 
but  the  obvious  fact  that  environment  does  strongly  affect 
and  modify  individual  function  and  structure  and  the  rea- 
sonable belief  that  the  modification  of  the  race  must  ulti- 
mately rest  on  and  proceed  from  the  modification  of  the 
individual,  make  the  theories  of  orthogenesis  based  on  en- 
vironmental influence  very  suggestive  and  of  distinct 
scientific  value.  In  addition,  too,  there  is  a  certain  amount 
of  actual  evidence  of  observation  for  orthogenesis :  an 
evidence  of  two  categories,  namely,  positive  affirmative 
evidence,14  and  negative  evidence  drawn  from  the  inade- 
quacy of  other  theories,  notably  natural  selection,  to  explain 
certain  observed  phenomena  which  can  be  explained  on  the 
assumption  of  an  orthogenesis.  The  general  character  of 
this  evidence  is  indicated  in  our  first  paragraph  treating  of 
orthogenesis.  To  this  may  be  added  an  ab- 

stract  of  Plate's'!  r6sum6  of  the  facts  .or 

to  prove  ortho-  phenomena  which  may  be  looked  on  as  positive 
evidence  for  orthogenesis  (although  Plate  cau- 
tiously notes  that  some  of  these  may  be  only  phenomena  of 
orthoselection).  These  phenomena  pointing  toward  ortho- 
genesis may  be  grouped  into  six  categories : 

i.  The   "analogous   or  parallel   variations"   which   have 
been  recognised  ever  since  Darwin's  time,  he,  himself,  list- 
ing many  examples  of  them.     These  are  varia- 
Ta^1ne(lismsin  tions  of  unmistakably  similar  character,  which 
often  appear  in  different  branches  of  the  same 
large    group.     "Comparative    anatomy    reveals    many    ex- 


280  DARWINISM   TO-DAY. 

amples  to  show  that  a  definite  or  determinate  direction  of 
modification  may  be  noted  in  all  the  sub-groups  of  a  large 
family,  although  appearing  in  unequal  degree  in  different 
species.  Examples  are  the  reduction  of  the  hind  toes  among 
the  Artiodactyls  which  has  continued  in  several  genera 
(giraffe,  camel,  llama)  up  to  a  complete  disappearance,  and 
the  modification  of  the  originally  single  genital  duct  into  a 
double  and  finally  triple  one,  as  occurs  in  both  the  Pul- 
monata  and  the  Opisthobranchiata.  Often  a  progressive 
development  can,  on  mechanical  or  physical  grounds,  come 
about  by  a  modification  in  but  one  direction,  and  may  lead 
thus  to  convergent  changes,  as  the  development  of  a  lens  in 
a  pigment  fleck  in  the  case  of  many  unrelated  lower  animals, 
the  similarity  of  the  heart  in  crocodiles,  birds,  and  mammals, 
the  appearance  of  a  placenta  with  Permales  among  the 
Marsupials  and  also  among  the  Placentalia." 

2.  The  numerous  "excessive  structures"  which  are  de- 
veloped far  beyond  the  limits  of  usefulness.    Examples,  the 

tusks  of  the  wild  boar  (Babirussa  alfurus) ;  the 

sations"SpeCial1"  ^ant  norns  °f  rnany  wild  sheep  and  goats ; 
the  enormously  elongated  thread-like  neck  of 
several  Rhynchophorous  beetles,  as  Apoderus  tenuissimus, 
etc.;  the  absurdly  long  eye-stalks  of  such  crustaceans  as 
Macrophthahnus  laterillei  and  Podophthalmus  vigil;  Meso- 
plodon,  whose  mouth  can  be  opened  but  a  little  when 
the  animal  is  full  grown  because  on  each  side  an  under 
tooth  grows  around  the  upper  jaw.  Such  "excessive 
structures"  have  undoubtedly  led  to  the  dying  out  of  many 
former  species :  examples,  the  tusks  of  the  mammoth,  the 
antlers  of  the  Irish  stag,  the  canines  of  Smilodon  neogaus. 

3.  "The  constitution,  or  actual  chemical  composition  of  the 
body  permits,  in  many  cases,  changes  only  in  few  directions. 
The  animal  or  plant  breeder  may  by  no  means  produce  any 
wished-for  form  or  colour.     No  one  has  yet  succeeded  in 
producing  a  blue  Maiblume,  a  grass  with  divided  leaves,  a 


OTHER   THEORIES   OF   SPECIES-FORMING.       281 

hen  with  a  parrot's  beak.     And  we  can  declare  with  con- 
fidence that  a  chorda  dorsalis  can  never  appear  in  a  beetle. 
_      .     .     .   Through  the  very  fact  that  an  animal  belongs 

Constitutional  .....  .  .     . 

limitations  on  to  a  group  the  possibilities  of  variation  are 
variation,  distinctly  delimited  and  in  many  special  cases 

these  possibilities  may  indeed  be  very  narrow."  Plate 
does  not  mention  in  this  connection  the  fact  that  some 
biologists  have  seen  in  this  restriction  of  the  range  of  varia- 
tion which  inevitably  accompanies  specialisation  in  the 
development  of  animal  groups  an  important  factor  in  the 
determination  of  lines  of  descent.  Cope  gave  much  import- 
ance to  this  factor,  and  very  recently  Rosa,16  in  a  most  in- 
genious and  suggestive  paper,  attributes  to  this  "progressive 
reduction  of  variability"  a  large  importance  in  the  dying 
out  of  old  species  and  the  origin  of  new  ones. 

4.  "By  the  correlations  which  bind  each  organ  to  others 
the  range  of  variation  is  also  restricted." 

5.  Many  facts  of  palaeontology  seem  to  prove  the  existence 
of  orthogenetrc  evolution.    "Wherever  a  large  supply  of  ma- 
Facts  from       terial  permits  the  working  out  of  a  phyletic 

paleontology       series,  we  always  see  a  limited  number  of  lines 

supporting  or- 
thogenesis,         of  development,  which  'despite  occasional  side- 
branching  run  essentially  in  straight  lines,  in  steps  which 
lead  gradually  one  to  another." 

6.  The  phyletic  series  (chains  of  forms)  of  recent  species 
Single  phy-      a^so  snow>  where  we  are  able  to  trace  them, 

letic  lines.          distinctive   single   lines  of  development. 

Eimer's  particular  theory  of  orthogenesis,  which  we 
have  chosen  as  a  representative  of  the  orthogenetic  doc- 
trine in  general  (although  few  biologists  who  believe  in 
the  principle  of  orthogenesis  accept  this  theory  in  detail), 
may  be  briefly  stated  as  follows : 

Modifications  of  organisms,  that  is,  lines  of  evolution,  are 
not  miscellaneous,  but  occur  according  to  control  along  a 
few  definite  directions,  these  lines  of  change  being  deter- 


282  DARWINISM   TO-DAY. 

mined  not  at  all,  at  least  in  their  beginnings,  by  selection  on 
a  basis  of  utility,  but  as  the  result  of  the  inheritance  of  ac- 
quired characters  and  according  to  the  laws 
of  organic  growth  (organophysis).  The  prin- 
cipal  effects  of  these  laws  of  organic  growth  are 
made  manifest  by  the  determinant  evolution,  or  orthogenesis, 
which  obtains,  and  which  is  in  direct  contrast  to  that  kind  of 
evolution  which  natural  selection,  if  it  really  effected  any- 
thing, would  bring  about.  For  evolution  by  natural  selec- 
tion would  occur  along  all  sorts  of  heterogeneous  and  radiat- 
ing lines  which  is,  according  to  Eimer,  actually  not  the 
case.  A  few  definite  lines  obtain  from  which  occasional 
branches  are  given  off,  the  whole  building  the  familiar 
phyletic  or  genealogical  tree.  That  these  main  lines  and 
branches  are  not  themselves  the  result  of  selection  is  proved 
by  the  fact  that  much  evolution  and  modification  of  organ- 
isms is  not  directly  useful,  a  majority,  indeed,  of  the  char- 
acters distinguishing  different  species  not  being  characters 
of  utility.17  Only  when  a  character  or  line  of  evolution 
becomes  of  a  life-and-death-determining  disadvantage  can 
selection  interfere  with  evolution  by  orthogenesis.  And  this 
interference  is  always  and  only  of  the  nature  of  a  stamping 
•out,  never  of  the  character  of  the  creation  of  new  characters 
or  lines.  Eimer  believes  in  the  inheritance  of  acquired 
characters,  believes  in  a  considerable  species-forming  influ- 
ence of  geographical  isolation,  that  is,  finds  such  isolation 
very  helpful  to  the  general  basic  organic  growth  evolution 
principle  and  finds  the  actual  causes  of  orthogenesis  "to 
lie  in  the  effects  of  external  influences,  climate,  nutrition, 
on  the  given  constitution  of  the  organism."  "This  is  not 
Lamarckism,"  Eimer  points  out,  anxious  to  have  his  theory 
to  his  own  credit,  "for  Lamarck  ascribed  to  the  external  in- 
fluences no  effects  on  the  animal  body,  and  only  very  little 
on  the  plant  body."  Eimer  adds  that  the  effects  of  external 
influences  are  usually  considered  a  part  of  Lamarckism; 


OTHER   THEORIES   OF   SPECIES-FORMING.       283 

.as  a  matter  of  fact  Lamarck's  species-forming  influences 
were,  chiefly  at  least,  the  inherited  results  of  actual  use  or 
disuse,  or  of  other  functional  stimulation  initiated  or  exer- 
cised actively  by  the  organism  itself.  In  the  actual  varia- 
tion of  organisms  Eimer  sees  none  of  that  "oscillation"  or 
equal  variation  around  a  median  or  modal  point  character- 
istic of  the  Darwinian  conception,  but  sees  always  a  deter- 
minate variation  in  a  few  definite  lines.  He  denies  positively 
any  capacity  on  the  part  of  natural  selection  to  create  species, 
finding  it  effective  in  breaking  the  continuous  organic  chain, 
that  is,  of  separating  it  into  species,  only  when  aided  by 
geographical  isolation.  The  actual  species-forming,  that  is, 
the  breaking  up  into  specific  units  of  the  orthogenetic  lines 
of  change  instituted  by  his  dynamic  factors,  he  finds  to  de- 
pend on  three  chief  moments,  viz.,  a  standing  still  or  cessa- 
tion of  development  (Enturicklungsstillstand)  ;  a  sudden  de- 
velopment by  leaps,  called  halmatogenesis  (which  is  almost 
exactly  the  fundamental  idea  in  Korschinsky's  and  de  Vries's 
later  heterogenesis  theory)  ;  and  third,  a  hindrance  or  difri- 
'Cttlty  in  reproduction  (which  is  the  essential  factor  in  Ro- 
manes's theory  of  physiological  selection  proposed  ten  years 
later).  It  is  of  interest  to  note  Eimer 's  claim  to  the  original 
conception  of  species-forming  both  by  heterogenesis  and 
through  physiological  selection,  with  which  two  theories 
the  names  of  de  Vries  and  Romanes,  respectively,  are  com- 
monly associated  as  those  of  the  original  proposers. 

Of  Eimer's  three  species-forming  factors  he  lays  most 
stress  on  the  one  I  have  first  mentioned  viz.,  Entwicklungs- 
stillstand.  "The  origin  of  species  depends  essentially  on 
Entwicklungsstillstand  or  Genepistase,  that  is,  the  standing 
still  of  certain  forms  at  definite  stages  in  the  developmental 
line,  while  others  go  on."  This  permits  of  the  origin  of 
numerous  different  species  in  the  same  locality  or  region, 
without  any  need  of  isolation.  As  orthogenesis  modifies, 
that  is,  causes  to  vary  in  the  same  way,  many  individuals  at 


284  DARWINISM   TO-DAY. 

a  time,  it  is  easy  to  see  that  if  some  of  these  produce  young 
which  do  not  proceed  farther  along  the  orthogenetic  line, 
that  is,  do  not  vary  farther,  while  others  produce  progeny 
that  tend  to  move  on  along  the  line  or  lines  of  determinate 
variation,  new  species  can  be  dropped,  as  it  were,  out  of  th^ 
general  course  of  the  orthogenetic  evolution  all  along.  An^ 
if  these  persist  we  have  a  series  of  distinct  organic  forms  all 
related  chainwise  although  living  simultaneously  and  in  the 
same  region.  This  cessation  of  development  can  lead  to 
many  added  new  forms  when  it  occurs  in  the  form  of 
Heterepistase,  that  is,  where  only  a  few  characteristics  re- 
main fixed  at  some  early  developmental  stage  while  others 
go  on.  By  the  fixing  or  cessation  of  development  in  differ- 
ent small  groups  of  characteristics,  and  in  different  combina- 
tions of  these  groups  many  new  species  may  result.  All 
cases  of  so-called  atavism  are  interpreted  by  Eimer  simply 
as  examples  of  his  Entwicklungsstillstand,  this  cessation  of 
development  occurring  in  the  atavistic  organs  at  a  very  early 
stage. 

We  should  not  omit  mention,  in  connection  with  Eimer's 
theory,  of  a  point  upon  which  he  lays  great  stress,  and  that 
is  that  his  theory  is  not  the  result  of  pure  speculation,  but  is 
the  unavoidable  conclusion  arrived  at  by  long  years  of 
specific  observations  and  study  of  the  facts  obtaining  in  the 
ease  of  the  relations,  conditions,  and  course  of  evolution  of 
certain  groups  of  organisms.  Eimer  made  careful  and  ex- 
tended studies  of  the  wing-patterns  of  two  large  groups  of 
butterflies,  and  of  certain  lizards  and  birds,  and  it  is  on  the 
basis  of  these  studies  in  particular  that  his  theory  was 
formulated.  It  is  certainly  to  be  admitted  that  his  exhaust- 
ive and  most  suggestive  account  of  the  relations  of  species 
and  patterns  in  the  swallow-tailed  and  certain  other  butter- 
flies makes  a  very  strong  argument  against  the  validity  of 
natural  selection  as  an  explanation  of  these  conditions.  And 
the  example  of  Eimer's  prolonged  and  ^minute  study  of 


OTHER   THEORIES   OF   SPECIES-FORMING.        285 

actual  facts  as  a  basis  for  his  theory  and  hypothesis  building 
is  one  which  has  not  been  always  followed  by  biological 
generalisers.  It  is  to  be  regretted  that  the  polemical  and 
personal  character  of  much  of  Eimer's  writing  has  tended 
to  make  his  whole  work  less  regarded  than  it  ought  to  be 
by  biologists. 

That  Eimer's  theory  does  not  include  in  any  degree  the 
assumption  of  an  inner  directive  or  progressive  force  the 
following  quotation  from  Eimer  himself  shows :  "Accord- 
ing to  my  investigations  the  chief  cause  of  transformation 
[of  species]  is  that  determined  definitive  organic  growth 
(organophysis)  whose  expression  is  a  definite  determined 
development  (orthogenesis),  which  is  imposed  on  the 
plasma  by  constant  outer  influences,  climate,  and  nourish- 
ment. .  .  .  Apart  from  the  fact  that  the  Nagelian  assump- 
tion of  a  definite  determined  development  is  a  hypothetical 
one,  not  proved  by  facts,  the  zoologist  can  hardly  accept  the 
existence  of  such  a  dominant  inner  factor  ever  pushing 
toward  advance,  when  he  recalls  the  host  of  regressive  struc- 
tures which  he  has  to  see.  This  tendency  to  progress  based 
on  the  assumption  of  'inner  growth  laws'  contradicts 
flatly  the  assumption  of  outer  influences  as  causes  of 
change.  .  .  .  And  it  is  my  belief  that  it  is  precisely 
these  outer  influences,  and  the  physiological  phenomena 
dependent  on  them,  which  are  the  determining  factors  in 
the  phyletic  development  just  as  they  are  in  individual 
development." 

Among  American  biologists  who  have  been  believers,  in 
some  degree,  in  Lamarckism  or  some  other  form  of  ortho- 
genetic  evolution,  Cope  is  the  one  who  has  most 
dennitely  formulated  his  beliefs  into  a  complete 
theory  of  the  method  of  creating  and  guiding 
variation  and  descent  lines.  Cope's  theory  may  be  called 
one  of  bathmism  (growth-force), kinetogenesis  (direct  effect 
of  use  and  disuse  and  environmental  influence),  and  arch- 


286  DARWINISM   TO-DAY. 

aesthetism  (influence  of  primitive  consciousness).  In  an 
essay 19  first  published  by  Cope  in  1871  the  following- 
hypotheses  were  presented.  (These  hypotheses  are  stated 
here  in  Cope's  own  words,  quoted  from  the  preface  of  his 
book  "The  Origin  of  the  Fittest,"  1887)  : 

"i.  The  law  of  repetitive  addition,  in  which  the  structures 
of  animals  were  shown  to  have  originated  from  simple 
repetitions  of  identical  elements. 

"2.  The  existence  of  an  especial  force  which  exhibits 
itself  in  the  growth  of  organic  beings,  which  was  called 
growth-force,  or  bathmism. 

"3.  That  development  consists  in  the  location  of  this 
energy  at  certain  parts  of  the  organism. 

"4.  That  this  location  was  accomplished  by  use  or  effort, 
modifying  and  being  modified  by  the  environment;  or  the 
doctrine  of  kinetogenesis. 

"5.  That  the  location  of  this  energy  at  one  point  causes  its 
abstraction  from  other  points,  producing  'complementary 
diminution'  of  force  at  the  latter. 

"6.  That  the  location  of  this  energy,  so  as  to  produce  the 
progressive  change  called  evolution,  is  due  to  an  influence 
called  'grade  influence.' 

"7.  That  inheritance  is  a  transmission  of  this  form  of 
energy,  which  builds  in  precise  accord  with  the  sources 
from  which  it  is  derived. 

"8.  That  this  'grade  influence'  is  an  expression  of  the  in- 
telligence of  the  animal,  which  adapts  the  possessor  to  the 
environment  by  an  'intelligent  selection.' 

"9.  An  attempt  to  account  for  the  origin  of  'mimetic 
analogy'  by  'maternal  impressions.'  " 

In  later  writings  20  Cope  subdivides  his  kinetogenesis  prin- 
ciple, or  the  influence  of  use,  disuse,  and  environment,  into 
a  physico-chemical  influence  affecting  the  organism  through 
molecular  effects,  which  he  calls  physiogenesis,  and  a  me- 
chanical influence  affecting  the  organism  through  molar 


OTHER  THEORIES   OF   SPECIES-FORMING.        287 

effects,  for  which  the  term  kinetogenesis  is  retained.  The 
modifications  produced  by  these  two  classes  of  influences 
"are  supposed  to  be  the  result  of  the  action  of  the  causes  in 
question  continued  throughout  geologic  time."  These 
modifications  are  assumed  to  be  inherited.  In  the  animal 
kingdom  kinetogenesis,  or  the  modifying  influence  of  mo- 
tion, is  assumed  to  be  the  more  potent  efficient  cause  of 
evolution;  in  the  plant  kingdom,  physiogenesis.  The  gen- 
eral standpoint  of  Cope's  theory  is  thus  strictly  Lamarckian. 
But  he  adds  to  this  reformulation  of  general  Lamarckism  a 
remarkable  feature  which  he  calls  archaesthetism.  This  is 
the  doctrine  that  "animal  movements  are  primitively  deter- 
mined by  sensibility  or  consciousness"  and  that  this  "con- 
sciousness has  been  and  is  one  of  the  primary  factors  in  the 
evolution  of  animal  forms."  That  is,  the  kinetogenesis 
which  is  the  chief  causo-mechanical  factor  of  the  evolution 
of  the  animal  kingdom,  from  primitive  single-cell  type  to 
most  complex  Metazoan,  has  for  its  own  initiation  conscious 
effort.  Thus  Cope  is  forced  to  assume,  which  he  does,  that 
"conscious  states  have  preceded  organisms  in  time  and 
evolution."  The  formal  statement  of  this  phenomenon, 
then,  has  to  be  the  thesis  that  energy  can  be  conscious.  "If 
true,"  writes  Cope,  "this  is  an  ultimate  fact,  neither  more 
nor  less  difficult  to  comprehend  than  the  nature  of  energy 
or  matter  in  their  ultimate  analyses.  But  how  is  such  a. 
hypothesis  to  be  reconciled  with  the  facts  of  nature,  where 
consciousness  plays  a  part  so  infinitesimally  small?  The 
explanation  lies  close  at  hand,  and  has  been  already  referred 
to.  Energy  become  automatic  is  no  longer  conscious,  or  is 
about  to  become  unconscious."  Cope  holds  then  that  "con- 
sciousness was  coincident  with  the  dawn  of  life,"  and  that 
"evolution  is  essentially  .a  process  of  mind.  The  source  of 
the  consciousness,  which  is  back  of  it,  is  at  present  an  un- 
solved problem." 

Cope  was  a  palaeontologist,21  and  his  belief  in  the  necessity 


288  DARWINISM   TO-DAY.   - 

of  some  factor  or  factors  besides  that  of  natural  selection 
to  explain  evolution  lines  as  revealed  by  palgeontological 
study  is  shared  by  a  large  majority  of  the  recognised 
American  palaeontologists.  Osborn  of  Columbia,  Williston 
of  Chicago,  Hyatt  of  Boston,  Smith  of  Stanford,  studying 
respectively  the  fossil  mammals,  the  reptiles,  and  the 
molluscs,  all  voice  their  belief  in  the  existence  of  evidence  in 
the  history  of  the  evolution  of  these  animal  groups  for 
orthogenetic  variation  and  descent. 

Recently  Whitman,  the  Nestor  of  American  zoologists, 

has  declared  himself  strongly  as  an  adherent  of  the  actuality 

of   orthogenetic   evolution.      For    many    years 

expression  in       Whitman  has  been  studying  the  variations  and 

favour  of  ortho-    inheritance  in  pigeons,  and  through  this  work 


in  particular  he  has  become  convinced  that 
species-forming  variation  does  advance  in  a  definite  direc- 
tion as  well  as  in  various  directions.  He  says,22  "natural 
selection,  orthogenesis,23  and  mutation  appear  to  present 
fundamental  contradictions ;  but  I  believe  that  each  stands 
for  truth,  and  reconciliation  is  not  distant.  The  so-called 
mutations  of  (Enothera  are  indubitable  facts ;  but  two  lead- 
ing questions  remain  to  be  answered.  First,  are  these  muta- 
tions now  appearing,  as  is  agreed,  independently  of  varia- 
tion, nevertheless  a  production  of  variations  that  took  place 
at  an  earlier  period  in  the  history  of  these  plants?  Sec- 
ondly, if  species  can  spring  into  existence  at  a  single  leap, 
without  the  assistance  of  cumulative  variations,  may  they 
not  also  originate  with  such  assistance?  That  variation 
does  issue  a  new  species,  and  that  natural  selection  is  a 
factor,  though  not  the  only  factor,  in  determining  results, 
is,  in  my  opinion,  as  certain  as  that  grass  grows  although 
we  cannot  see  it  grow.  Furthermore,  I  believe  I  have 
found  indubitable  evidence  of  species-forming  variation 
advancing  in  a  definite  direction  (orthogenesis),  and  like- 
wise of  variations  in  various  directions  (amphigenesis).  If 


OTHER   THEORIES   OF   SPECIES-FORMING.        289 

I  am  not  mistaken  in  this,  the  reconciliation   for  natural 
selection  and  orthogenesis  is  at  hand"  (p.  4). 

In  the  category  of  determinate  or  orthogenetic  variation 

should  be  included  Delage's  24  not  very  clearly  distinguished 

variation  generate.     "We  call  by  the  name  of 

Delage's  the-  6  J 

ory  of  general      general  variation,    he  says,    that  which  appears 


a^.  Qne  ^me  jn  ajj  ^  individuals  of  a  race  or 
at  least  a  large  number  of  individuals  and  which  affects, 
most  often,  several  characteristics,  if  not  all,  in  various 
degrees  of  strength.  Variations  of  this  sort  must  be  due 
to  modifications  of  the  germ  plasm  produced  either  by  the 
reducing  division,  or  by  fertilisation,  or  by  accidental  altera- 
tions which  this  plasm  undergoes  in  its  various  divisions." 
It  is  to  these  variations,  according  to  Delage,  that  species- 
change  is  due.  The  inducing  influences  which  result  in  the 
appearance  of  general  variations  are  use  and  disuse  and  the 
"conditions  of  life"  (nutrition  and  climate). 

As  forming  a  sort  of  link  between  the  theories  of  ortho- 
genesis and  those  of  heterogenesis  (to  be  discussed  in  the 

next  chapter),  may  be  mentioned  the  rather 
theory  of  vague  and  unformed  theory  of  Jaeckel,25  the 

metakinesis,  Berlin  paleontologist,  called  "metakinesis." 
Jaeckel  believes,  from  a  study  of  fossil  animal  series,  that 
there  exists  evidence  of  orthogenetic  descent,  but  that  while 
genera  and  families  may  show  continuous  phyletic  series, 
species  appear  sporadically,  suddenly,  and  without  special 
reference  to  the  phyletic  series.  He  believes  that  many  cases 
of  epistasis  occur  :  that  is,  that  many  sexually  mature  ani- 
mals show  arrests  of  development  in  early  ontogenetic 
stages,  and  have  therefore  given  up  a  former  further 
development.  He  finds  numerous  examples  of  this  condi- 
tion among  fossil  crindids  and  trilobites  and  living  sela- 
chians. What  his  theory  of  metakinesis  really  seems  to  be 
is  a  combination  of  the  sudden,  definitive  appearance  of  new 
species,  which  is  the  essential  conception  in  the  theories  of 


290  DARWINISM   TO-DAY. 

heterogenesis  (explained  in  the  next  chapter),  with  the 
determinate  lines  of  change  or  descent,  which  is  the  essential 
idea  in  orthogenesis. 

APPENDIX. 

1  Lamarck,  1744-1828,  the  "founder  of  the  complete  modern  theory 
of   descent,   is   the   most   important   figure    [in   the   history  of  the 

References  to  theory  of  evolution]  between  Aristotle  and  Darwin'* 
Lamarck's  (Osborn,  "From  the  Greeks  to  Darwin,"  p.  156,  1899). 

writings,  jj's  tneory  of  descent  and  the  causes  of  descent  was 

presented  in  his  "Philosophic  Zoologique,"  a  large  work  published  in 
1809.  For  a  brief  account  of  Lamarck's  life  and  work,  see  Osborn, 
"From  the  Greeks  to  Darwin,"  pp.  156-181,  1899.  For  an  exhaustive 
account  with  full  quotations  from  Lamarck's  exposition  of  his  the- 
ories, see  Packard,  "Lamarck,  His  Life  and  Work,"  1901.  For  ex- 
positions of  the  Lamarckian  point  of  view  compared  with  the  Dar- 
winian position,  see  Haeckel,  E.,  "Die  Naturanschauung  von  Darwin, 
Goethe,  und  Lamarck,"  1882;  Lang,  A.,  "Zur  Characteristik  der  For- 
schungswege  von  Lamarck  und  Darwin,"  1889;  Ward,  L.  F.,  "Neo- 
Darwinism  and  Neo-Lamarckism,"  Proc.  Biol.  Soc.,  Wash.,  Vol.  VI, 
pp.  11-71,  1891;  Hutton,  F.  W.,  "Darwinism  and  Lamarckism,  Old 
and  New,"  1899;  Pauly,  A.,  "Darwinismus  und  Lamarckismus,"  1905. 

2  Among  the  more  conspicuous  of  these  cases  are  Brown-Sequard's 
epileptic  guinea-pigs,   Hyatt's  Planorbis  shells,   Cunningham's  flat- 

Brown-Se-  fishes,  and  Fischer's  butterflies.  Morgan,  in  "Evo- 
qnard's  experi-  lution  and  Adaptation,"  gives  the  following  account 
ments  on  guinea-  an(j  discussion  of  the  Brown-Sequard  experiments 
and  results :  "The  best  direct  evidence  in  favour  of  the 
Lamarckian  argument  is  that  furnished  by  the  experiments  of  Brown- 
Sequard.  He  found,  as  the  result  of  injury  to  the  nervous  system  of 
guinea-pigs,  that  epilepsy  appeared  in  the  adult  animal,  and  that  young 
born  from  these  epileptic  parents  became  also  epileptic.  Still  more 
important  was  his  discovery  that,  after  an  operation  on  the  nerves, 
as  a  result  of  which  certain  organs,  the  ear  or  the  leg,  for  instance, 
are  affected,  the  same  affection  appears  in  the  young  born  from 
such  parents.  These  results  of  Brown-Sequard  have  been  vouched 
for  by  two  of  his  assistants,  and  his  results  in  regard  to  the  inheri- 
tance of  epilepsy  have  been  confirmed  by  Obersteiner,  and  by 
Luciani  on  dogs.  Equally  important  is  their  later  confirmation,  as 
far  as  the  main  facts  go,  by  Romanes. 

"Brown-Sequard  gives  the  following  summary  of  his  results. 
I  follow  Romanes'  translation  in  his  book  on  'Darwin  and  After 


OTHER   THEORIES   OF   SPECIES-FORMING.        291 

Darwin,'  where  there  is  also  given  a  careful  analysis  of  Brown- 
Sequard's  results,  as  well  as  the  outcome  of  the  experiments  of 
Romanes  himself.  The  summary  is  as  follows: — 

"i.  'Appearance  of  epilepsy  in  animals  born  of  parents  which  had 
been  rendered  epileptic  by  an  injury  to  the  spinal-cord. 

"2.  'Appearance  of  epilepsy  also  in  animals  born  of  parents 
which  had  been  rendered  epileptic  by  section  of  the  sciatic  nerve. 

"3.  'A  change  in  the  shape  of  the  ear  in  animals  born  of  parents 
in  which  such  a  change  was  the  effect  of  a  division  of  the  cervical 
sympathetic  nerve. 

"4.  'Partial  closure  of  the  eyelids  in  animals  born  of  parents  in 
which  that  state  of  the  eyelids  had  been  caused  either  by  section 
of  the  cervical  sympathetic  nerve,  or  the  removal  of  the  superior 
cervical  ganglion. 

"5.  'Exophthalmia  in  animals  born  of  parents  in  which  an  injury 
to  the  restiform  body  had  produced  that  protrusion  of  the  eyeball. 
This  interesting  fact  I  have  witnessed  a  good  many  times,  and  seen 
the  transmission  of  the  morbid  state  of  the  eye  continue  through 
four  generations.  In  these  animals  modified  by  heredity,  the  two 
eyes  generally  protruded,  although  of  the  parents  usually  only  one 
showed  exophthalmia,  the  lesion  having  been  made  in  most  cases 
only  on  one  of  the  corpora  restiformia. 

"6.  'Hsematoma  and  dry  gangrene  of  the  ears  in  animals  born 
of  parents  in  which  these  ear  alterations  had  been  caused  by  an 
injury  to  the  restiform  body  near  the  nib  of  the  calamus. 

"7.  'Absence  of  two  toes  out  of  the  three  of  the  hind-leg,  and 
sometimes  of  the  three,  in  animals  whose  parents  had  eaten  up 
their  hind-leg  toes,  which  had  become  anaesthetic  from  a  section 
of  the  sciatic  nerve  alone,  or  of  that  nerve  and  also  of  the  crural. 
Sometimes,  instead  of  complete  absence  of  the  toes,  only  a  part 
of  one  or  two  or  three  was  missing  in  the  young,  although  in 
the  parent  not  only  the  toes,  but  the  whole  foot  was  absent 
(partly  eaten  off,  partly  destroyed  by  inflammation,  ulceration,  or 
gangrene). 

"8.  'Appearance  of  various  morbid  states  of  the  skin  and  hair 
of  the  neck  and  face  in  animals  born  of  parents  having  had  similar 
alterations  in  the  same  parts  as  effects  of  an  injury  to  the  sciatic 
nerve.' 

"Romanes,  who  later  went  over  the  same  ground,  in  part  under 
the  immediate  direction  of  Brown-Sequard  himself,  has  made  some 
important  observations  in  regard  to  these  results,  many  of  which 
he  was  able  to  confirm. 

"He  did  not  repeat  the  experiment  of  cutting  the  cord,  but  he 
found  that,  to  produce  epilepsy,  it  was  only  necessary  to  cut  the 


292  DARWINISM   TO-DAY. 

sciatic  nerve.  The  'epileptiform  habit'  does  not  appear  in  the  animal 
until  some  time  after  the  operation;  it  lasts  for  some  weeks  or 
months,  and  then  disappears.  The  attacks  are  not  brought  on  spon- 
taneously, but  by  'irritating  a  small  area  of  the  skin  behind  the 
-ear  on  the  same  side  of  the  body  as  that  on  which  the  sciatic  nerve 
had  been  divided.'  The  attack  lasts  for  only  a  few  minutes,  and 
•during  it  the  animal  is  convulsed  and  unconscious.  Romanes  thinks 
that  the  injury  to  the  sciatic  nerve,  or  to  the  spinal  cord,  produces 
some  sort  of  a  change  in  the  cerebral  centres,  'and  that  it  is  this 
change — whatever  it  is,  and  in  whatever  part  of  the  brain  it  takes 
place — which  causes  the  remarkable  phenomena  in  question/ 

"In  regard  to  Brown-Sequard's  statements,  made  in  the  3d  and 
the  4th  paragraphs,  in  respect  to  the  results  of  the  operation  of 
cutting  the  cervical  sympathetic,  Romanes  had  not  confirmed  the 
results  when  his  manuscript  went  to  press;  but  soon  afterward, 
after  Romanes'  death,  a  note  was  printed  in  Nature,  by  Dr.  Hill, 
announcing  that  two  guinea-pigs  from  Romanes'  experiment  had 
been  born,  'both  of  which  exhibited  a  well-marked  droop  of  the 
upper  eyelid.  These  guinea-pigs  were  the  offspring  of  a  male  and 
female  in  both  of  which  I  had  produced  for  Dr.  Romanes,  some 
months  earlier,  a  droop  of  the  left  upper  eyelid  by  division  of  the  left 
cervical  sympathetic  nerve.  This  result  is  a  corroboration  of  the 
series  of  Brown-Sequard  experiments  on  the  inheritance  of  acquired 
characters.' 

"Romanes  states  that  he  also  found  that  injury  to  a  particular 
spot  of  the  restiform  bodies  is  quickly  followed  by  a  protrusion 
of  the  eye  on  the  same  side,  and  further,  that  he  had  'also  had 
many  cases  in  which  some  of  the  progeny  of  parents  thus  affected 
have  shown  considerable  prptrusion  of  the  eyeballs  of  both  sides, 
and  this  seemingly  abnormal  protrusion  has  occasionally  been 
transmitted  to  the  next  generation.  Nevertheless,  I  am  far  from 
satisfied  that  this  latter  fact  is  anything  more  than  an  accidental 
coincidence.'  This  reservation  is  made  on  the  ground  that  the 
protrusion  in  the  young  is  never  so  great  as  in  the  parents,  and 
also  because  there  is  amongst  guinea-pigs  a  considerable  amount 
of  individual  variation  in  the  degree  of  prominence  of  the  eye- 
balls. Romanes,  while  unwilling  to  deny  that  an  'obviously  abnor- 
mal amount  of  protrusion,  due  to  the  operation,  may  be  inherited 
in  lesser  degree,'  is  also  unwilling  to  affirm  so  important  a  conclu- 
sion on  the  basis  of  these  experiments  alone. 

"In  regard  to  Brown-Sequard's  6th  statement,  Romanes  found 
after  injury  to  the  restiform  body  that  haematoma  and  dry  gan- 
grene may  supervene,  either  several  weeks  after  the  operation,  or 
at  any  subsequent  time,  even  many  months  afterward.  The  disease 


OTHER   THEORIES   OF   SPECIES-FORMING.        293 

usually  affects  the  upper  parts  of  both  ears,  and  may  then  gradually 
extend  downward  until  nearly  the  whole  ear  is  involved.  'As  re- 
gards the  progeny  of  animals  thus  affected  in  some  cases,  but  by 
no  means  in  all,  a  similarly  morbid  state  of  the  ears  may  arise 
apparently  at  any  time  in  the  life  history  of  the  individual.  But 
I  have  observed  that  in  cases  where  two  or  more  individuals  of  the 
same  litter  develop  this  diseased  condition,  they  usually  do  so  at 
about  the  same  time,  even  though  this  may  be  months  after  birth, 
and  therefore  after  the  animals  are  fully  grown.'  Moreover,  the 
morbid  process  never  extends  so  far  in  the  young  as  it  does  in  the 
parents,  and  'it  almost  always  affects  the  middle  third  of  the  ear/ 
Several  of  the  progeny  from  this  first  generation,  which  had  appa- 
rently inherited  the  disease,  but  had  not  themselves  been  directly 
operated  upon,  showed  a  portion  of  the  ear  consumed  apparently 
by  the  same  disease.  Romanes  then  gives  the  following  signifi- 
cant analysis  of  this  result.  Since  a  different  part  of  the  ear 
of  the  progeny  is  affected,  and  also  a  Very  much  less  quantity 
thereof,  it  might  seem  that  the  result  was  due  either  to  a  mere 
coincidence,  or  to  the  transmission  of  microbes.  But  he  goes  on 
to  say,  that  he  fairly  well  excluded  both  of  these  possibilities,  for, 
in  the  first  place,  he  has  never  observed  'the  very  peculiar  process 
in  the  ears,  or  in  any  other  parts  of  guinea-pigs  which  have  neither 
themselves  had  the  restiform  bodies  injured,  nor  been  born  of 
parents  thus  mutilated.'  In  regard  to  microbes,  Romanes  tried  to 
infect  the  ears  of  normal  guinea-pigs  by  first  scarifying  these  parts, 
and  then  rubbing  them  with  the  diseased  surfaces  of  the  ears  of 
affected  guinea-pigs.  In  not  a  single  case  was  the  disease  produced. 

"Romanes  concludes  that  these  'results  in  large  measure  corrobo- 
rate the  statements  of  Brown-Sequard;  and  it  is  only  fair  to  add 
that  he  told  me  they  were  the  results  which  he  had  himself  obtained 
most  frequently,  but  that  he  had  also  met  with  many  cases  where  the 
diseased  condition  of  the  ears  in  parents  affected  the  same  parts  in 
their  progeny  and  also  occurred  in  more  equal  degrees.' 

"We  come  now  to  the  remarkable  conclusion  given  in  Brown- 
Sequard' s  7th  statement,  in  regard  to  the  absence  of  toes  in  animals 
whose  parents  had  eaten  off  their  own  hind  toes  and  even  parts 
of  their  legs.  Romanes  got  neuroses  in  the  animals  operated  upon, 
and  found  that  the  toes  might  be  eaten  off;  but  none  of  the  young 
showed  any  defect  in  these  parts.  Furthermore,  Romanes  repeated 
the  same  operation  upon  the  descendants  through  six  successive 
generations,  so  as  to  produce,  if  possible,  a  cumulative  effect,  but  no 
inheritance  of  the  mutilation  was  observed.  'On  the  other  hand, 
Brown-Sequard  informed  me  that  he  had  observed  this  inherited 
absence  of  toes  only  in  about  one  or  two  per  cent,  of  cases.'  It  is 


294  DARWINISM   TO-DAY. 

possible,  therefore,  Romanes  adds,  that  his  own  experiments  were 
not  sufficiently  numerous  to  have  obtained  such  cases. 

"In  this  connection  I  may  give  an  account  of  some  observa- 
tions that  I  made  while  carrying  out  some  experiments  in  telegony 
with  mice.  I  found  in  one  litter  of  mice  that  when  the  young  came 
out  of  the  nest  they  were  tailless.  The  same  thing  happened  again 
when  the  second  litter  was  produced,  but  this  time  I  made  my 
observation  sooner,  and  examined  the  young  mice  immediately  after 
birth.  I  found  that  the  mother  had  bitten  off,  and  presumably 
eaten,  the  tails  of  her  offspring  at  the  time  of  birth.  Had  I  been 
carrying  on  a  series  of  experiments  to  see  if,  when  the  tails  of  the 
parents  were  cut  off,  the  young  inherit  the  defect,  I  might  have 
been  led  into  the  error  of  supposing  that  I  had  found  such  a  case  in 
these  mice.  If  this  idiosyncrasy  of  the  mother  had  reappeared  in 
any  of  her  descendants,  the  tails  might  have  disappeared  in  suc- 
ceeding generations.  This  perversion  of  the  maternal  instincts  is 
not  difficult  to  understand,  when  we  recall  that  the  female  mouse 
bites  off  the  navel-string  of  each  of  her  young  as  they  are  born, 
and  at  the  same  time  eats  the  afterbirth.  Her  instinct  was  carried 
further  in  this  case,  and  the  projecting  tail  was  also  removed. 

"Is  it  not  possible  that  something  of  this  sort  took  place  in 
Brown-Sequard' s  experiment?  The  fact  that  the  adults  had  eaten 
off  their  own  feet  might  be  brought  forward  to  indicate  the  possi- 
bility of  a  perverted  instinct  in  this  case  also.  At  least  my  obser- 
vation shows  a  possible  source  of  error  that  must  be  guarded 
against  in  future  work  on  this  subject. 

"In  regard  to  the  8th  statement  of  Brown-Sequard,  as  to  various 
morbid  states  of  the  skin,  Romanes  did  not  test  this,  because  the 
facts  which  it  alleges  did  not  seem  of  a  sufficiently  definite  character. 

"These  experiments  of  Brown-Sequard,  and  of  those  who  have 
repeated  them,  may  appear  to  give  a  brilliant  experimental  confirma- 
tion of  the  Lamarckian  position ;  yet  I  think,  if  I  were  a  Lamarckian, 
I  should  feel  very  uncomfortable  to  have  the  best  evidence  in  sup- 
port of  the  theory  come  from  this  source,  because  there  are  a 
number  of  facts  in  the  results  that  make  them  appear  as  though 
they  might,  after  all,  be  the  outcome  of  a  transmitted  disease,  as 
Weismann  claims,  rather  than  the  inheritance  of  an  acquired  char- 
acter. Until  we  know  more  of  the  pathology  of  epilepsy,  it  may 
be  well  not  to  lay  too  great  emphasis  on  these  experiments.  It 
should  not  be  overlooked  that  during  the  long  time  that  the  embryo 
is  nourished  in  the  uterus  of  the  mother,  there  is  ample  opportu- 
nity given  for  the  transmission  of  material,  or  possibly  even  of 
bacteria.  If  it  should  prove  true  that  epilepsy  is  due  to  some  sub- 
stance present  in  the  nervous  system,  such  substances  could  get 


OTHER   THEORIES   OF    SPECIES-FORMING.         295 

there  during  the  uterine  life  of  the  embryo.  Even  if  this  were  the 
tase,  it  may  be  claimed  that  it  does  not  give  an  explanation  of  the 
local  reappearance  of  the  disease  in  the  offspring.  But  here,  also, 
we  must  be  on  our  guard,  for  it  is  possible  that  only  certain  regions 
of  the  body  are  susceptible  to  a  given  disease;  and  it  has  by  no 
means  been  shown  that  the  local  defect  itself  is  inherited,  but  only 
the  disease.  Romanes  insists  that  a  very  special  operation  is  neces- 
sary to  bring  about  certain  forms  of  transmission." 

The  case  of  the  Planorbis  shells  studied  by  Hyatt  (Proc.  Amer. 
Phil  Soc.,  Vol.  XXXII,  p.  615  ff.)  has  been  interestingly  dis- 
Hyatt's  studies  cussed  by  Le  Dantec  ("Traite  de  Biologic,"  pp.  296 
of  Planorbis,  ff.,  1903)  as  follows:  "On  trouve,  dans  les  terrains 
tres  anciens,  des  coquilles  de  Cephalopodes  qui  ont  la  forme  d'une 
corne  de  vache  et  dont  la  section  transversale  est  a  peu  pres  circu- 
laire;  en  suivant  la  serie  des  fossiles  de  cette  categoric  dans 
des  terrains  plus  recents,  on  constate  que  ces  coquilles,  presque 
droites  naguere,  se  sont  enroulees  de  plus  en  plus  a  la  maniere 
d'une  spirale  d'Archimede;  nous  ne  connaissons  pas  la  raison 
de  cette  transformation,  mais  la  presence  de  certains  caracteres 
communs  permet  de  considerer  comme  demontre  que  les  formes 
enroulees  descendent  des  animaux  a  coquilles  droites.  Or,  1'enroule- 
ment  est  tellement  fort  dans  certains  types  que  les  tours  de 
spire  successifs  s'impriment  les  uns  dans  les  autres,  donnant  nais- 
sance  a  un  sillon  dorsal  dont  la  genese  mecanique  est  evidente, 
puisqu'il  resulte  sans  conteste  de  la  pression  du  tour  de  spire 
precedent  sur  le  suivant. 

"Tant  que  les  animaux  en  question  restent  aussi  nettement 
enroules,  on  peut  admettre  que  ce  caractere  de  1'existence  d'un  sillon 
dorsal  est  acquis  individuellement  par  chaque  Cephalopode  pour  des 
raisons  mecaniques  evidentes,  le  contact  des  tours  de  spires. 

"Mais  voila  qu'a  une  periode  plus  recente  de  1'histoire  du  monde, 
les  decouvertes  paleontologiques  nous  montrent  que  les  descendants 
de  ces  Cephalopodes  a  coquille  enroulee  ont  subi  un  commencement 
de  deroulement  et  ont  maintenant  la  forme  d'une  spirale  d'Archi- 
mede a  tours  de  spires  plus  ecartes  les  uns  des  autres  et  ne  se 
touchant  plus ;  et  notez  bien  que  des  caracteres  communs  permettent 
d'affirmer  que  ces  Cephalopodes  a  moitie  deroules  descendent  de 
ceux  dont  1'enroulement  etait  beaucoup  plus  serre. 

"Or,  chose  admirable,  le  sillon  dorsal  persiste  chez  ces  etres  a 
coque  a  moitie  deroulee!  Cependant  il  n'y  a  plus  maintenant 
pression  d'un  tour  de  spire  sur  le  tour  de  spire  precedent;  nous 
avons  compris  mecaniquement  la  genese  de  ce  sillon  dorsal,  quand 
les  tours  de  spire  se  touchaient  et  se  pressaient  1'un  1'autre ;  et'  ce 
sillon  persiste  en  dehors  des  conditions  mecaniques  ou  il  a  etc 


296  DARWINISM   TO-DAY. 

d'abord  produit;  il  se  transmet  a  des  descendants  dont  la  coquille 
est  deroulee !  C'est  done  que  le  patrimoine  hereditaire  a  ete 
modifie  sous  I'lnfluence  de  la  production  mecanique  de  ce  sillon 
dorsal,  au  point  de  devenir  adequat  a  cette  forme  nouvelle  d'equi- 
libre ;  il  y  a  un  nouveau  patrimoine  hereditaire,  qui  construisant  un 
individu  nouveau  et  son  squelette,  fera  apparaitre,  sans  pression, 
le  sillon  dorsal!" 

The  results  of  the  experiments  of  Cunningham  on  flatfishes  are 
stated  by  the  author,  in  a  paper  on  "The  Problem  of  Variation," 
Nat.  Sci.,  Vol.  Ill,  p.  285,  1893.  Cunningham  put  the  very  young: 
fish,  while  still  bilaterally  symmetrical  (in  which  stage  the  pigment 
is  equally  developed  on  both  sides  of  the  body),  into  aquaria  lighted 
from  below.  He  found  that  when  the  young  fish  begins  to  undergo 
its  metamorphosis,  the  pigment  gradually  disappears  on  one  side, 
as  it  would  have  done  under  normal  conditions,  i.  e.,  when  they  are 
lighted  from  above.  If,  however,  the  "fish  are  kept  for  a  short  time 
longer,  lighted  from  below,  the  pigment  begins  to  come  back  again. 
"The  first  fact,"  says  Cunningham,  "proves  that  the  disappearance 
of  the  pigment-cells  from  the  lower  side  in  the  metamorphosis  is  a 
hereditary  character,  and  not  a  change  produced  in  each  individual 
by  the  withdrawal  of  the  lower  side  from  the  action  of  the  light. 
On  the  other  hand,  the  experiments  show  that  the  absence  of  pig- 
ment-cells from  the  lower  side  throughout  life  is  due  to  the  fact  that 
light  does  not  act  upon  that  side,  for,  when  it  is  allowed  to  act, 
pigment-cells  appear.  It  seems  to  me  that  the  only  reasonable  con- 
clusion from  these  facts  is  that  the  disappearance  of  the  pigment- 
cells  was  originally  due  to  the  absence  of  light,  and  that  the  change 
has  now  become  hereditary.  The  pigment-cells  produced  by  the 
action  of  light  on  the  lower  side  are  in  all  respects  similar  to- 
those  normally  present  on  the  upper  side  of  the  fish.  If  the  dis- 
appearance of  the  pigment-cells  was  due  entirely  to  the  variation 
of  the  germ-plasm,  no  external  influences  could  cause  them  to  re- 
appear ;  and  if  there  were  no  hereditary  tendency,  the  coloration 
of  the  lower  side  of  the  flatfish  would  be  rapid  and  complete." 

Concerning  Fischer's  highly  interesting  experimental  work,  I 
quote  the  following  paragraph  from  Fuchs,  H.  (Biol.  Centralbl., 
Fischer's  ex-  Vo1-  XXI»  PP-  SQi-592,  1901 ;  Fischer's  own  papers 
periments  with  have  been  published  in  various  biological  journals, 
Iratterfliesi  the  particular  one  recounting  the  results  obtained; 

with  Arctia  caja  in  the  Allg.  Zeitschr.  fur  Entomologie,  Vol. 
VI,  1902)  : 

"Experimentelle  Untersuchungen,  ob  es  moglich  sei,  durch  will- 
kurliche,  geeignet  gewahlte  Veranderungen  der  'ausseren  Lebens- 
bedingungen/  besonders  der  Temperaturverhaltnisse,  im  Tierreiche 


OTHER   THEORIES   OF   SPECIES-FORMING.        297 

Variationen  bei  den  Arten  hervorzurufen,  wurden  in  den  letzten 
Decennien  wiederholt  angestellt;  mit  Vorliebe  hat  man  sich  dabei 
als  Versuchsobjekte  die  Schmetterlinge  gewahlt :  ich  erinnere  z. 
B.  an  die  schonen  Versuche  von  Standfuss  und  E.  Fischer.  Das 
Resultat  war — wie  ja  nach  unseren  heutigen  Anschauungen  iiber 
den  ziichtenden  Einfluss  der  Faktoren  der  Aussenwelt  auf  alle. 
Organismen  eigentlich  kaum  anders  zu  erwarten  stand — positiv. 
Eine  Frage  allerdings,  an  welche  bei  diesen  Untersuchungen  wohl 
jeder  der  Forscher  dachte,  namlich :  ob  die  auf  solche  Weise 
erworbenen  Eigenschaften  und  Abanderungen  auch  auf  die  eventu- 
ellen  Nachkommen  iibertragen,  also  vererbt  wurden  oder  doch 
wenigstens  werden  konnten,  blieb  dabei  einstweilen  unentschieden. 
Erst  kurzlich  gelang  es  E.  Fischer,  auch  fur  dieses  Postulat  der 
modernen  Biologic  einen  vollgiltigen  Beweis  beizubringen.  F.  expe- 
rimentierte  mit  Arctia  caja,  dem  braunen  Bar,  der  ja  auch  den 
meisten  Laien — meist  wohl  unter  dem  Namen  'deutscher  Bar' — 
bekannt  sein  durfte,  ein  erfahrungsgemass  fur  kiinstliche  Varia- 
tionsversuche  besonders  geeignetes  Tier.  Durch  willkiirlich  ge- 
wahlte  Temperaturveranderungen,  und  zwar  durch  intermittierende 
Abkiihlungen  bis  auf — 8°  C.,  denen  die  Puppen  wiederholt  ausge- 
setzt  wurden,  erzielte  F.  stark  aberrative  Falter,  und  zwar  aberrativ 
nicht  nur  bezuglich  der  'Farbe  und  Zeichnung' — wenn  auch  hier  in 
erster  Linie. — sondern  auch  bezuglich  der  Form,  z.  B.  der  Fliigel 
und  der  Beine.  Dabei  hebt  F.  ausdrucklich  hervor,  dass  in  letzterer 
Hinsicht  es  sich  nicht  etwa  um  Verkriippelungen  handelte,  sondern 
'die  Fiisse  waren  kraftig  und  mit  gut  ausgebildeten  Krallen 
versehen.'  Unter  diesen  Varietaten  gelangen  nun  mehrfache 
Kreuzungen ;  die  Puppen  dieser  Zucht  wurden  unter  normalen 
Bedingungen  erhalten.  Und  siehe !  von  den  alsbald  ausgeschliipften 
Tieren  zeigte  eine  nicht  unerhebliche  Anzahl  die  Variationen  der 
Eltern,  und  zwar  im  allgemeinen  als  Kombinationen  aus  den 
veranderten  Eigenschaften  beider  Eltern,  so  dass  einige  mehr  dem 
elterlichen  Mannchen  glichen,  andere  mehr  dem  elterlichen  Weib- 
chen.  Es  ist  dieses  also,  wie  F.  sagt,  ein  experimenteller  Beweis, 
dass: 

"i.  die  Art  durch  die  Faktoren  der  Aussenwelt  Veranderungen 
erfahrt,  und  dass 

"2.  diese  Veranderungen  sich  auf  die  Nachkommen  iibertragen. 

"Die  Thatsache  der  Vererbung  erworbener  Eigenschaften  steht 
mithin  fest,  wenn  wir  auch  iiber  das  Wesen  der  ratselhaften  dabei 
stattfindenden  Vorgange,  auf  Grund  dieser  Untersuchungen,  natiir- 
lich  absolut  noch  nichts  sagen  konnen." 

To  the  above  cases  of  the  alleged  inheritance  of  acquired  charac- 
ters I  may  add  some  account  of  certain  experiments  with  the  mul- 


DARWINISM   TO-DAY. 

berry  silkworm  carried  on  by  R.  G.  Bell  and  myself.  (For  detailed  ac- 
count of  this  work  see  Science,  N.  S.,  Vol.  XVIII,  pp.  741-748,  1903.) 

"One  of  the  races  of  the  mulberry  silkworm,  Bombyx  mori,  has 
been  the  subject  of  experiments  directed  toward  a  determination  of 
the  exact  quantitative  relation  which  quantity  and  quality  of  food 
bear  to  the  development  and  variations  of  the  individual  insect  and 
its  progeny.  .  .  . 

"The  insect,  Bombyx  mori,  has  a  complete  metamorphosis,  tak- 
ing no  food  as  an  adult,  so  that  the  experimental  control  of  the 
Experiments  feeding  has  been  necessary  only  during  the  larval  or 
with  silkworms,  'silkworm'  stage.  The  larval  life  is  subdivided  into 
five  stages  clearly  set  off  from  one  another  by  the  intervening 
moults,  of  which  there  are  normally  four,  and  these  substages  have 
been  useful  when  an  alteration  of  food  conditions  during  a  sharply  de- 
fined shorter  time  than  the  entire  larval  life  was  desirable.  .  .  .  The 
change  in  quantity  of  food  has  consisted  in  altering  the  amount  of 
mulberry  leaf  served  to  the  larvae,  the  control  of  which  has  bee.n 
secured  as  follows :  It  has  been  determined  through  experience  with 
normal  larvae  that  each  will  consume  a  certain  amount  of  food  in 
a  certain  number  of  hours  (increasing  in  amount  with  the  increas- 
ing age  and  size  of  the  larva),  this  amount  representing  the 
optimum  amount  of  food  for  the  normal  individual  and  necessitating 
as  many  daily  meals  as  are  required  to  keep  any  but  the  moulting 
larva  constantly  supplied  with  fresh  food.  This  amount  determined, 
a  tolerably  definite  small  proportion  of  the  optimum  amount  has 
been  allotted  the  individuals  which  were  sentenced  to  short  rations, 
which,  roughly  speaking,  might  be  listed  as  one-quarter  the  optimum 
amount  during  earlier  stages  and  one-eighth  during  the  late  larval 
.stages.  This  one-fourth,  one-eighth,  or  whatever  it  may  have  been 
numerically,  was,  at  any  rate,  as  small  an  amount  of  food  as  was 
compatible  with  mere  life.  .  .  . 

"These  experiments  have  extended  over  a  period  of  three  years, 
covering  as  many  generations  of  the  insect.  The  data  gathered 
(being  the  measurements,  weight,  and  duration  of  each  larva  in  each 
of  its  five  states;  the  time  of  spinning,  weight  of  silk  and  weight 
and  duration  of  each  pupa ;  and  the  weight,  size,  pattern,  and 
fertility  of  female  of  each  imago)  furnish  material,  then,  for  a 
study  of  the  effects  of  under-feeding  upon  individuals  during  a 
single  generation  (the  1903  generation  or  that  of  1902  or  1901), 
during  two  successive  generations  (1901-02  or  1902-03),  and  two 
alternating  generations  (1901-1903)  and  during  three  generations 
(1901-03),  a  control  lot  having  been  carried  for  each  experimental 
lot  so  that  what  is  modified  may  confidently  be  distinguished  from 
what  is  normal.  .  .  . 


OTHER   THEORIES    OF   SPECIES-FORMING.        299 

"In  these  variously-fed  worms  there  exists  a  very  definite  and 
constant  relation  between  amount  of  food  and  size  as  indicated  by 
weight,  the  starveling  individuals  being  consistently  smaller  than 
the  well-nourished,  the  lingering  effects  of  this  dwarfing  being 
handed  down  even  unto  the  third  generation,  although  the  progeny 
of  the  famine  generation  be  fed  the  optimum  amount  of  food;  in 
case  the  diminished  nourishment  is  imposed  upon  three,  or  even 
two  successive  generations,  there  is  produced  a  diminutive,  but 
still  fertile,  race  of  Lilliputian  silkworms,  whose  moths,  as  regards 
wing  expanse,  might  join  the  ranks  of  the  micro-Lepidoptera 
almost  unremarked. 

"In  illustration  may  be  quoted  the  typical  or  modal  larval  weights 
for  each  of  the  lots  of  1903  at  the  time  of  readiness  to  spin,  which 
marks  the  completion  of  the  feeding  and  is,  therefore,  an  advan- 
tageous point  for  a  summary  of  the  results  of  the  three  years' 
experimental  feeding. 

"The  history  of  the  eight  lots  referred  to  may  be  gathered  from 
an  examination  of  the  accompanying  table,  in  which  'O'  means 
optimum  amount  of  food  and  'S'  means  short  rations.  The  column 
to  the  right  indicates  the  relative  rank  of  the  various  lots  as  judged 
by  the  modes  of  frequency  polygons  erected  to  include  all  the 
individual  weights  for  each  lot  at  spinning  time. 


Lot  Number. 

HISTORY  OF  LOTS. 

Modal  Rank. 
1903. 

IQOI. 

Grandparents. 

IQO2. 

Grandparents. 

1903. 

I 

O 
0 

o 
o 

s 
s 
s 

S        ' 

0 

o 

s 
s 

0 
0 

s 
s 

o 
s 
o 
s 
o 
s 

0 

s 

I 
6 
3 
7 

2 

5 

8 

2     

•3    .. 

r 

6  

•j    

8 

"We  find  that  control  lot  I,  consisting  of  normally-fed  indi- 
viduals of  normal  ancestry,  holds  first  rank  in  weight,  as  was  to  be 
expected.  Second  comes  lot  5,  whose  grandparents  experienced  a 
famine  but  whose  parents  as  well  as  themselves  enjoyed  years  of 
plenty.  Lots  2  and  3  have  likewise  had  one  ancestral  generation  on 
.short  rations,  and  the  fact  that  they  are  lighter  in  weight  than  lot 


DARWINISM   TO-DAY. 

5  illustrates  a  general  rule  which  obtains  throughout  the  entire 
company  of  experimental  worms,  namely,  that  the  effects  of  famine 
grow  less  evident  the  further  removed  the  individuals  are  from  its 
occurrence  in  their  ancestral  history.  Thus  lot  5  is  two  generations 
removed  from  the  famine  of  1901,  while  lot  3  has  had  but  one 
generation  in  which  to  recover  its  ancestral  loss.  Lot  2,  which 
has  had  a  total  of  but  one  famine  year — the  current  year — neverthe- 
less ranks  below  lot  7,  which  has  had  two  famine  years  in  its 
ancestry  succeeded  by  plenty  during  the  current  year.  Lot  2  also 
ranks  below  lot  6,  a  fact  which  appears  strange,  considering  that 
lot  6  has  suffered  two  generations  of  famine,  including  the  current 
year,  which  is  the  only  famine  year  experienced  by  lot  2.  In 
explanation  of  this  anomalous  condition  it  is  suggested  that  possibly 
the  larvae  of  lot  6  were  better  fitted  for  enduring  and  making  the 
best  of  hard  conditions  than  were  the  individuals  of  lot  2,  the 
ancestors  of  the  former  lot  having  been  selected  two  years  ago 
on  a  food-scarcity  basis.  This  suggestion  gathers  support  from  an 
inspection  of  the  mortality  notes,  from  which  it  appears  that  the 
number  of  deaths — for  which  the  famine  was  probably  a  contributing 
and  not  a  primary  cause — in  each  lot  which  is  for  the  first  time 
subjected  to  short  rations  is  almost  doubly  greater  than  the  num- 
ber of  deaths  in  lots  which  are  descended  from  starved  ancestors, 
whether  these  ancestral  famines  occurred  in  successive  or  alternate 
years.  The  figures  indicate  that  a  reduction  of  food  is  almost  twice 
as  destructive  upon  the  first  generation  which  is  subjected  to  it  as 
it  is  when  visited  on  a  second  generation.  Lot  4  follows  lot  2  as 
the  seventh  in  rank  and  its  position  is  in  accord  with  the  rule  above 
noted,  its  latest  ancestral  generation  which  enjoyed  an  optimum 
amount  of  food  during  1902  or  1903.  Lot  8  holds  lowest  rank, 
it  and  its  ancestors  having  been  subject  to  trying  conditions  through- 
out the  entire  three  years,  during  some  one  or  two  of  which  all 
the  other  lots  have  enjoyed  the  best  of  food  conditions.  Thus  it 
appears  that  a  generation  of  famine  leaves  its  impression  upon  at 
least  the  three  generations  which  succeed  it,  yet  the  power  of 
recovery  through  generous  feeding  exhibited  by  the  progeny  of 
individuals  subjected  to  famine,  is  so  extensive  (witness  lot  5) 
that  it  appears  probable  that  every  trace  left  by  the  famine  upon 
the  race  would  eventually  disappear.  It  is  even  conceivable  that  the 
ultimate  result  of  the  famine  would  be  a  strengthening  of  the  race, 
the  famine  having  acted  the  part  of  a  selective  agent,  preserving 
only  the  strong. 

"But  although  there  is  a  large  difference  between  the  well  fed 
and  the  poorly  fed,  there  persists,  more  obviously  in  late  than  in 
early  life,  a  very  considerable  discrepancy  as  to  size  among  the 


OTHER   THEORIES   OF   SPECIES-FORMING.        301 

individuals  of  each  single  lot  whose  environment,  in  so  far  as  food, 
temperature,  room,  humidity,  etc.,  constitute  it,  is  identical. 

"For  example,  referring  again  to  the  weights  at  spinning  time  of 
the  larvae  of  1903,  it  is  true  that,  although  each  lot  has  a  modal 
class  of  weights  to  which  the  majority  of  its  individuals  belong  and 
about  which  the  rest  of  the  lot  distributes  itself  rather  symmetrically, 
the  extremes  are  surprisingly  distant  from  one  another.  Thus  in 
lot  i  (the  normal  control  lot)  the  extremes  are  1,540  and  2,530 
mg. ;  in  lot  2,*  800  and  1,402  mg. ;  in  lot  3,  1,180  and  2,170  mg. ; 
in  lot  4,  690  and  1,204  mg- ;  in  lot  5,  1,370  and  2,100  mg. 

"That  is  to  say,  identical  feeding  has  not  made  identical  full- 
grown  larvae  out  of  individuals  which  undoubtedly  varied  congeni- 
.tally  at  the  start,  those  variations — in  embryo — standing  at  birth  in 
the  same  relation  to  one  another  that  they  stand  in  the  adults,  hav- 
ing merely  been  smaller  and  less  readily  discernible  in  early  life, 
although  manifestly  present  in  delicately  measurable  degree  in  the 
earliest  records  made  upon  normal  individuals.  For  example, 
weight  measurements  taken  immediately  after  the  second  moult, 
range  in  one  lot  from  21  to  39  mg.,  or  60  per  cent,  of  the  modal 
weight,  while  the  weights  in  this  same  lot  at  spinning  time,  some 
five  weeks  later,  range  from  534  to  2,080  mg.,  or  85  per  cent,  of 
the  mode  for  the  lot.  These  embryonic  but  potentially  large  varia- 
tions have  simply  'grown  up'  along  with  the  insect  and  are  as  truly 
congenital  in  the  adult  as  they  were  in  the  newly  hatched  larva. 
This  would  seem  to  place  quite  conclusively  in  the  category  of 
congenital  variations  some  part  of  those  variations  (in  size  and  pro- 
portions of  parts)  which  are  commonly,  and  properly  to  some 
degree,  called  acquired. 

"That  conditions  of  alimentation  bear  a  directive  relation  to  func- 
tional activity,  may  be  demonstrated  by  reference  to  the  records  of 
the  physiological  functions  of  moulting,  spinning,  pupating,  and 
emerging,  of  the  individuals  of  the  experimental  lots. 

"An  abnormal  extension  of  the  time  needed  for  the  metamor- 
phosis follows  upon  a  reduction  of  the  food  supply.  The  degree 
of  extension  depends  with  the  utmost  nicety  upon  the  amount  of 
food  given  the  larvae.  For  example,  among  the  1901  generation  of 
silkworms,  one  control  lot  of  twenty  larvae  was  given  the  optimum 
amount  of  food,  a  second  lot  of  twenty  larvae  one-half  this  amount, 
and  a  third  lot  of  twenty  larvae  one-quarter  of  the  amount.  To 
take  the  time  of  the  fourth  moulting  as  an  illustration,  the  moulting 
was  begun  by  the  first  lot,  which  led  the  way  by  two  and  a  half 
-days,  at  the  end  of  which  the  second  lot  began  to  moult,  while 

*  See  table,  next  page,  for  the  history  of  each  lot. 


302 


DARWINISM    TO-DAY. 


the  third  lot  was  twenty-four  hours  behind  the  second.  All  the 
individuals  of  the  first  lot  had  finished  moulting  on  April  20,  all 
of  the  second  on  April  24,  while  the  moulting  in  the  third  lot  con- 
tinued until  April  29. 

"As  in  the  matter  of  weight,  this  retarding  of  the  functions,  by 
means  of  a  reduced  food  supply,  affects  not  only  the  immediate 
generation  which  is  subjected  to  the  famine,  but  the  lingering  effects 
of  it  may  be  traced  in  the  progeny  of  the  dwarfed  individuals  at 
least  unto  the  third  generation,  even  though  two  years  of  plenty 
follow  the  one  year  of  famine.  The  conditions  which  obtain  in 
each  lot  of  individuals  of  the  1903  generation  at  spinning  time  are 
shown  in  the  accompanying  table,  which  is  based  upon  polygons 
erected  to  include  all  the  individuals  in  each  lot. 


RANK  OF  1903  LOTS  AS  TO  PROMPTNESS 

IN  SPINNING. 

Lot 

When  Two-thirds  of  Each  Lot 

Num- 

were Spinning. 

ber. 

1901. 
Grand- 
parents. 

IQ02. 

Parents. 

1903. 

Spinner. 

Date. 

In  Order 
of  Rank. 

Latest 
Spinner. 

I  

o 

O 

o 

I 

May  12 

I 

I 

2  

o 

o 

s 

5 

25 

4 

4 

3  

o 

s 

0 

2 

13 

2 

3 

4  

0 

s 

s 

4 

26 

5 

5 

5  

s 

0 

o 

3 

13 

2 

2 

6.   ... 

s 

0 

s 

6 

29 

6 

7 

7  

s 

s 

o 

6 

22 

3 

5 

8  

s 

s 

s 

7 

30 

7 

6 

"This  period  in  the  life  of  the  silkworms  is  particularly  advan- 
tageous for  consideration  here,  because  it  marks  the  completion 
of  the  feeding,  so  that  the  individuals  of  under-fed  ancestry  have 
been  given  the  best  chance  to  recover,  while  those  subject  to  altered 
food  conditions,  had  had  the  benefit  of  the  alteration  during  the 
entire  food-taking  period  of  life. 

"In  the  table,  'O'  means  optimum  amount  of  food,  and  'S'  means 
short  rations.  To  the  right  of  the  history  of  the  lots  is  a  section 
showing  the  rank  of  the  lots  as  to  the  extreme  time  limits  of  the 
spinning  time  (emphasised  congenital  differences  again),  with  a 
safer  criterion,  as  to  their  relative  promptness,  in  the  column  be- 
tween the  extremes — a  column  of  figures  intended  to  show  the  rela- 
tive promptness  with  which  a  two-thirds  majority  of  the  larvae 


OTHER   THEORIES   OF    SPECIES-FORMING.        3°S 

in  each  lot  arrives  at  the  spinning  time,  this  proportion  being  taken 
to  represent  the  typical  condition  for  the  lot.  The  order  in  which 
the  lots  are  arranged  in  this  column  corresponds  in  a  general  way 
with  that  prevalent  for  the  weights  at  spinning  time,  and  the 
generalisations  indulged  in  there  may,  with  few  exceptions,  be 
applied  here.  The  lots  which  were  well  fed  during  the  1903 
generation  are  ahead  of  all  of  those  given  short  rations  in  1903, 
whatever  ancestry  they  may  have  had.  Lot  I  leads  here  as  in  the 
matter  of  weight.  Lots  3  and  5  tie  for  second  place,  having  held 
second  and  third  places  in  weight.  Lots  2  and  4  stand  in  the 
same  relation  to  one  another  that  they  held  as  to  weight.  Con- 
trary to  the  weight  relation,  lot  6  follows  lot  2  at  the  spinning — a 
fact  which  illustrates  again  the  general  rule  that  two  generations, 
of  famine  are  more  disastrous  than  one,  but  does  not  lend  support 
to  the  notion  of  natural  selection  on  a  food  scarcity  basis  as  pre- 
viously suggested.  Lot  8,  which  has  had  no  relief  from  famine 
during  the  entire  three  years,  brings  up  the  rear  at  the  spinning, 
as  might  be  expected. 

"This  check  upon  functional  activity  exercised  by  diminished  nour- 
ishment affects  the  moulting,  the  time  for  the  commencement  of 
spinning,  and  the  issuing  time  for  the  adults,  but  the  time  spent 
in  the  spinning  of  the  cocoon,  from  its  beginnings  in  the  threads, 
of  the  supporting  net  to  its  apparent  completion  when  the  cocoon 
becomes  opaque,  is  practically  identical  for  under-fed  and  well- 
fed  individuals.  A  reason  for  this  exception  to  the  tardy  habits 
of  the  under-fed  is  to  be  found  in  the  fact  that  the  under-fed 
larvae  produce  less  silk  (less  in  size,  thickness,  and  weight)  than  the 
well-fed,  thus  accomplishing  more  meager  results  in  the  same 
amount  of  time.  That  the  individuals  sentenced  to  short  rations 
should  produce  less  silk  than  their  well-fed  neighbours  is  certainly 
to  be  expected,  silk  not  being  made  without  leaves  any  more 
readily  than  bricks  without  straw. 

"Not  only  do  short  rations  protract  the  time  appointed  for  the 
spinning,  moulting,  etc.,  but  they  appear  to  have  a  more  striking 
effect  upon  the  actual  occurrence  of  the  moulting.  The  normal 
number  of  moults  for  the  silkworm  larva  is  four.  Five  moults 
have  occurred  for  most  of  the  individuals  belonging  to  the  under- 
fed lots  of  1902  and  1903,  whereas  none  of  the  well-fed  individuals 
has  undergone  a  fifth  moult.  It  would  seem,  therefore,  that  the 
occurrence  of  a  fifth  moult  may  be  fairly  ascribed  to  a  reduction  of 
food;  at  least  a  fifth  moult  very  frequently  accompanies  it  and  has 
suggested  the  possibility  that  the  enforced  fasting  of  the  under- 
fed larva — in  the  intervals  between  meals — may  have  the  same 
physiological  effect  as  the  normal  fasting  which  precedes  the  normal 


304  DARWINISM   TO-DAY. 

moulting,  during  which  time,  the  so-called  'moulting  fluid'  is 
secreted.  That  this  effect  may  accumulate  throughout  the  life- 
time of  the  larva  until  the  larva  is  actually  forced  to  indulge  in  the 
extravagance  (of  strength,  feeding  time,  and  body  wall  material) 
of  an  additional  moult  is  conceivable  and  will  justify  a  further 
test. 

"As  to  the  life-and-death  selection  due  to  famine,  it  may  be 
said,  in  addition  to  the  previous  discussion  of  mortality  among 
the  experimental  silkworms,  that  while  lots  subjected  to  two  years 
of  famine  (themselves  in  one  year,  their  parents  in  the  year  before) 
were  fertile  in  so  far  as  number  of  young  hatched  is  concerned,  it 
was  found  to  be  exceedingly  difficult  to  rear  from  them  a  1903 
generation.  Indeed,  at  the  time  of  the  second  moulting  there  were 
but  nineteen  individuals  (and  tolerably  vigorous  larvae  they  were) 
alive  in  the  lot  which  had  experienced  two  years  of  famine,  al- 
though every  individual  of  the  149  hatched  was  carefully  preserved 
and  royally  fed — a  fact  which  goes  to  prove  that  the  equipment  at 
birth  of  many  of  these  larvae  was  inadequate. 

'The  fact  that  some  larvae  of  starved  ancestry  have  exhibited  a 
superiority  over  their  fellows,  in  surviving  and  recovering  from 
hard  conditions,  is  testimony  for  the  existence  of  individual  varia- 
tions which  cannot  be  defined  anatomically,  and  yet  which  serve  as 
'handles'  for  natural  selective  agents.  Such  variations  might  be 
called  physiological  variations,  since  it  seems  that  the  surviving 
larvae  must  be  those  which  are  in  best  trim  physiologically.  These 
larvae  are  able  to  make  the  most  of  the  food  offered  to  them.  If 
competition  were  allowed,  they  would  probably  be  the  individuals 
which  would  cover  the  area  most  rapidly,  securing  whatever  food 
there  might  be.  But  under  our  experimental  conditions  there  was 
no  competition  allowed  and  yet  certain  precocious  individuals  made 
more  grams  of  flesh  and  more  yards  of  silk,  than  other  larvae 
furnished  with  the  same  amount  of  raw  material  under  like  con- 
ditions ;  that  this  was  due  to  the  possession  by  the  former  of  certain 
•congenital  qualities  of  adaptability  can  scarcely  be  doubted. 

"As  to  the  fertility  of  the  variously  fed  lots,  in  so  far  as  number 
of  eggs  produced  is  a  measure  of  fertility,  our  records  already 
demonstrate  the  fact  that  the  better  nourished  are  the  more  fertile. 
Furthermore,  the  economy  in  this  matter  practised  by  the  starve- 
lings is  not  merely  numerical,  quality  as  well  as  quantity  of  eggs 
being  affected.  In  witness  of  this  point  may  be  recalled  the  story 
of  the  dying  1903  generation,  produced  from  eggs  of  the  starvelings 
of  1901  and  1902,  which  would  seem  to  offer  conclusive  evidence 
that  a  famine  suffered  by  the  parents  works  its  way  into  the  germ- 
cells  so  that  most  of  their  progeny  have  but  a  poor  birthright." 


OTHER   THEORIES   OF   SPECIES-FORMING.       3°5 

For  special  discussions  of  the  inheritance  of  acquired  characters, 
see  the  following :  Roth,  E.,  "Die  Thatsachen  der  Vererbung,"  1885 ; 
Ziegler,  E.,  "Konnen  erworbene  pathologische  Eigenschaften  ver- 
erbt  werden  und  wie  entstehen  erbliche  Krankheiten  und  Missbil- 
dungen,"  1886;  Rohde,  F.,  "Uber  den  gegenwartigen  Stand  der 
Frage  nach  der  Entstehung  und  Vererbung  individuellen  Eigen- 
schaften und  Krankheiten,"  1896;  Osborn,  H.  F.,  "Are  Acquired 
Variations  Inherited,"  1890;  Elliott,  D.  G.,  "The  Inheritance  of 
Acquired  Characters,"  Auk,  Vol.  IX,  pp.  77-104,  1892;  Packard,  A. 
S.,  "On  the  Inheritance  of  Acquired  Characters  in  Animals  with 
Complete  Metamorphosis,"  Proc.  Amer.  Acad.  Science,  pp.  331- 
370,  1894;  Ritter,  W.  E.,  "On  the  Nature  of  Heredity  and 
Acquired  Characters,  and  the  Question  of  the  Transmissibility  of 
these  Characters,"  1900;  Wettstein,  R.  von,  "Der  Neo-Lamarckis- 
mus  und  seine  Beziehungen  zum  Darwinismus,"  1903;  Detto,  Carl, 
"Theorie  der  direkten  Anpassung,"  1904  (good  bibliography  of 
papers  on  plant  adaptations)  ;  Lendenfeld,  R.  V.,  "Variation  and 
Selection,"  Biol.  Centralbl,  Vol.  XXIII,  p.  489  ff.,  and  p.  563  ff., 
1903;  Pauly  A.,  "Darwinismus  und  Lamarckismus,"  1905;  Lotsy, 
J.  P.,  "Yorlesungen  iiber  Descendenztheorien,"  Vol.  I,  chap,  xii, 
1906;  Wheeler,  W.  M.,  "The  Polymorphism  of  Ants,"  Bull,  of 
Amer.  Mus.  Nat.  Hist.,  Vol.  XXIII,  pp.  1-93,  Plate  I- VI,  January, 
1907  (see  especially  pp.  50-00).  Certain  writers  of  sociologic  and 
philosophic  interests,  have  discussed  especially  the  possibility  of  the 
inheritance  of  acquired  mental  capacities  or  qualities  in  man;  ex- 
pressing a  belief  in  such  inheritance  are  Biichner,  "Die  Macht  der 
Vererbung  und  ihr  Einfluss  auf  der  moralischen  und  geistigen 
Fortschritt  der  Menschheit,"  1882,  and  Hartmann,  E.  V.,  "Philo- 
sophic des  Unbewussten,"  loth  ed. ;  against  such  an  inheritance  is 
Rawitz,  B.,  "Urgeschichte,  Geschichte,  und  Politik,"  1903.  Most 
important  of  all  the  discussions  of  the  inheritance  of  acquired  char- 
acters are  those  of  Weismann,  Spencer,  and  Eimer. 

A  recent  American  champion  of  Lamarckism  is  Caspar  L.  Red- 
field,  in  whose  writings  ("Control  of  Heredity,"  1903,  "Evolution 
Eedfield's  of  the  Setter,"  in  American  Field,  1904  and  1905,  and 
position,  "Breeding  of  the  Trotter,"  in  The  Horseman,  1905) 

is  urged  the  doctrine  that  acquired  mental  and  dynamic  qualities  are 
inherited.  On  a  host  of  data,  derived  from  the  pedigrees  and 
records  of  trotting  horses  and  setter  dogs,  Redfield  keenly  works  out 
his  inductions  regarding  the  inheritance  by  young  of  the  special 
qualities  due  to  training  and  practice  (acquirement)  of  the  parents; 
that  is,  the  best  offspring  (from  the  sportsman  breeder's  point  of 
view)  come  from  the  best  trained  parents.  There  is  a  great  deal 
of  ammunition  for  the  advocates  of  Lamarckism  in  Redfield's 


306  DARWINISM   TO-DAY. 

records,  although  his  too  sharp  distinction  between  structural  and 
functional  (so-called  "dynamic")  characters  is  not  at  all  helpful. 

The  most  recent  serious  treatment  of  the  problem  from  the  neo- 
Lamarckian  side,  and  one  of  great  interest  and  real  force,  is  that 
Montgomery's  °^  Montgomery  in  his  book  on  "The  Analysis  of 
explanation  of  Racial  Descent  in  Animals"  (1906).  Montgomery- 
inheritance  of  contends  that  there  can  be  no  congenital  variation- 
variation,  without  external  stimuli  (or  hybridisation)  to  initiate 
it,  because  germ-plasm  cannot  be  assumed  to  set  up  change  inde- 
pendently and  automatically,  as  this  would  be  almost  like  the 
assumption  of  spontaneous  generation.  Montgomery  says,  "When* 
the  process  of  heredity  proceeds  unchanged  the  ontogeny  of  one 
individual  is  just  like  that  of  its  parent.  When  a  change  of  the 
ontogeny  occurs,  so  that  the  offspring  comes  to  be  different  from 
its  parent,  we  say  that  a  variation  has  appeared  in  the  offspring. 
This  variation,  it  is  thinkable,  may  have  been  produced:  (i)  by- 
internal  growth  energies,  (2)  by  external  environmental  influences, 
or  (3)  by  a  combination  of  both;  and  it  is  necessary  to  discuss- 
which  one  of  these  is  the  most  probable. 

"There  is  clearly,  in  the  process  of  production  of  variation  and 
mutation,  some  modification  of  the  normal  process  of  heredity. 
Since  in  a  number  of  species  it  has  been  shown  that  all  the  adult 
individuals  from  one  locality  are  not  exactly  alike,  but  show  meas- 
urable differences  in  dimensions,  colour,  or  some  other  character, 
it  follows  that  the  hereditary  process  of  each  such  individual  must 
vary  correspondingly,  even  though  the  variation  does  not  become 
perceptible  until  the  stage  of  maturity.  The  origin  of  inherited, 
variation  or  mutation  is  then  a  question  of  the  origin  of  modifica- 
tion of  the  hereditary  process. 

"The  regularity  of  the  process  of  heredity  is  quite  comprehensi- 
ble on  the  basis  of  the  direct  transmission  of  definite  chromosomes 
in  number,  form,  and  quality  constant  for  the  species.  From  cell 
to  cell,  from  individual  to  individual,  these  chromosomes  are  regu- 
larly transmitted  in  a  continuous  progress,  therefore  a  succession  of 
similar  individuals  is  quite  understandable.  One  germ-cell  comes 
from  a  preceding  one,  to  our  knowledge  is  never  formed  from  a 
specialised  tissue-cell,  so  that  there  is  an  uninterrupted  passage  of 
the  germ-plasm  through  the  race.  This  is  Weismann's  idea  of  the 
continuity  of  the  germ-plasm,  which  we  will  paraphrase  as  the 
continuity  of  the  chromosomes. 

"A  variation  to  become  inherited  must  then  be  referable  to  a 
modification  of  the  energies  of  this  germ-plasm.  The  germ-plasm 
is  living  substance  of  proved  great  importance  in  the  metabolism  of: 
the  cell.  Though  in  a  sense  it  appears,  from  microchemical  re- 


OTHER   THEORIES   OF   SPECIES-FORMING.        307 

searches,  to  be  the  chief  agent  in  constructive  processes  of  the  cell, 
it  equally  appears  to  be  incapable  of  life,  or  unable  to  act  in  a 
normal  manner,  when  removed  from  the  influence  of  other  cell 
substances.  The  food  required  by  a  germ-cell  for  its  growth  is 
obtained  from  without  the  cell,  and  must  pass  through  the  cytoplasm, 
in  more  or  less  changed  condition,  to  reach  the  chromatin  within 
the  nucleus  and  there  be  elaborated  into  living  substance  and 
passed  over  to  the  cytoplasm  in  other  form.  This  conclusion  is 
drawn  from  both  experimental  and  microchemical  studies.  So  the 
oxygen  required  by  the  cell,  and  the  water,  must  be  obtained  from 
without  the  cell.  This  is  simply  in  agreement  with  the  general 
principle  that  no  body  can  increase  in  mass,  circumambient  condi- 
tions remaining  unchanged,  without  accretions  from  outside. 
Therefore,  the  germ-plasm  does  not  so  much  create  new  substances 
as  it  changes  substances  brought  to  it.  It  and  the  other  cell  con- 
stituents are  harmoniously  and  mutually  interdependent,  and  the 
ultimate  source  of  energies  of  these  substances,  all  connected  with 
the  elaboration  of  living  matter,  is  referable  to  external  agencies 
because  referable  to  food. 

''This  being  the  case,  the  energies  of  the  hereditable  substance, 
the  germ-plasm,  are  clearly  dependent  upon  influences  of  the  envi- 
ronment. This  conclusion  is  not  at  all  in  contradiction  with  the 
idea  of  the  continuity  of  the  chromosomes,  as  we  pointed  out  in 
the  preceding  chapter.  Therefore,  Weismann  was  in  error  when,  to 
support  his  idea  of  the  continuity  of  the  germ-plasm,  he  at  first 
argued  the  energies  of  the  germ-plasm  to  be  independent  of  body 
cells  and  of  the  environment  generally.  His  supposition  was  both 
unnecessary  for  the  view  of  the  continuity,  and  also  out  of  agree- 
ment with  the  phenomena.  The  ovum  cannot  elaborate  its  yolk 
substance  except  out  of  food  substance  received  from  without ; 
the  amount  of  its  food  substance  will  depend  upon  the  state  of 
nutritive  metabolism  of  the  individual  carrying  the  egg-cell ;  starva- 
tion of  that  individual  will  cause  cessation  of  energy  in  the  germ- 
cell,  and  ligaturing  of  the  blood-vessels  supplying  the  ovary  will 
produce  death  of  the  egg-cells.  The  results  of  observational  expe- 
rience teach  that  the  germ-plasm  is  not  a  little  god,  capable  of  self- 
existence  without  respect  to  external  agencies,  but  is  very  intimately 
bonded  to  the  latter.  Whether  the  germ-cell,  as  in  the  sponges,  be 
an  amoeboid  cell  which  wanders  about  in  the  body  tissues,  or 
whether  it  is  immovably  held  in  place  by  tissue-cells,  it  is  impossi- 
ble that  it  can  live  and  grow  without  receiving  and  reacting  to 
stimuli  from  these  tissue-cells.  The  egg-cells  of  many  animals  are 
set  free  in  water  before  they  commence  to  cleave  into  embryonic 
cells;  how  can  we  say,  then,  that  the  conditions  in  the  water  do 


308  DARWINISM   TO-DAY. 

not  influence  them?  They  will  die  if  removed  from  the  water,  and 
develop  abnormally  if  certain  substances  be  added  to  or  subtracted 
from  the  water.  But  the  embryonic  differentiation  is  a  result  of 
chromosomal  activities,  as  we  have  seen ;  therefore,  changes  in  the 
medium  must  influence  the  germ-plasm.  Is  not  a  well-recognised 
characteristic  of  living  matter,  response  to  external  stimuli  ?  How 
can  any  living  cell  be  acted  upon  by  stimuli  and  yet  not  react  to 
them?  There  is  not  a  single  observation  to  show  that  any  germ- 
cell,  or  its  germ-plasm,  is  in  any  way  guarded  or  protected  from 
external  stimuli,  either  by  the  structure  of  its  cell  wall  or  peripheral 
cytoplasm,  or  by  the  nature  of  the  living  tissue  that  encloses  it. 
And  whatever  affects  the  cell  body  must  indirectly  affect  the 
chromosomes,  because  of  the  physiological  connection  of  the  two. 

"From  such  considerations  it  would  seem  practically  certain  that 
the  energies  of  the  chromosomes  are  to  some  extent  respondent  to 
environmental  stimuli.  And  since  observation  shows  that  living 
matter  responds  differently,  if  not  always  according  to  the  nature 
of  the  stimulus  at  least  to  its  degree,  it  would  follow  that  change  in 
the  nature  or  degree  of  the  environmental  agencies  would  indirectly 
engender  change  in  the  activities  of  the  germ-plasm.  Not  to  admit 
this  would  be  to  deny  to  the  germ-plasm,  without  empirical  reason, 
properties  proven  for  all  other  living  substances. 

"This  thought  had  long  ago  been  expressed  clearly,  though  from 
a  different  line  of  reasoning,  by  Spencer  (1865).  We  may  state  it 
in  another  way.  Tissue-cells  are  granted  by  experimental  physiolo- 
gists the  ability  of  different  response,  or  different  intensity  of 
response,  to  stimuli  of  different  kind  or  degree.  But  a  tissue-cell 
is  a  lineal  descendant  of  a  germ-cell,  and  receives  germ-plasm 
from  the  latter.  Now  since  the  germ-plasm  has  been  transmitted 
continuously  to  the  tissue-cell,  must  not  the  energies  of  the  germ- 
plasms  of  the  two  be  alike  at  least  in  their  general  response 
activity?  Again,  a  Protozoan  may  be  considered  as  a  cell  not 
exactly  correspondent  to  a  germ-cell  of  a  Metazoan,  but  as  some- 
thing more,  as  a  unit  with  properties  of  both  a  germ-cell  and  a 
tissue-cell,  for  its  cytoplasmic  differentiations  (cilia,  contractile 
vacuoles,  cytopharynx,  etc.)  are  comparable  to  the  soma  of  a  Meta- 
zoan. In  the  case  of  the  Protozoan  Paramos cium,  Calkins  (1904) 
has  shown  that  the  reproductive  activity  is  increased  or  diminished 
according  to  the  amount  and  kind  of  food  stimuli.  Here,  then,  a 
Protozoan  has  its  reproductive  activities,  therefore  the  energies  of 
its  germ-plasm,  profoundly  influenced  by  environmental  changes; 
and  it  is  primarily  what  we  may  term  the  germ-cell  constituent  of 
the  Protozoan  that  becomes  influenced,  that  part  which  has  to  do 
with  reproduction  of  the  individual.  Weismann  considered  the 


OTHER   THEORIES   OF   SPECIES-FORMING.        3°9 

Protozoan  exactly  comparable,  in  the  sense  of  strict  continuity  of 
reproduction,  to  the  germ-cell  of  a  Metazoan,  and  yet  failed  to 
note  that  a  Protozoan  can  be  influenced  by  environmental  change. 

"Accordingly,  an  environmental  change  may  be  capable  of  induc- 
ing change  in  the  energies  of  the  germ-plasm.  The  expression  of 
the  energies  of  this  substance,  as  viewed  in  temporal  succession, 
constitutes  heredity.  Therefore,  the  process  of  heredity  may  become 
modified  by  a  change  in  the  environmental  conditions  of  the  germ- 
plasm.  And  since  we  defined  variation  as  a  modification  of  heredity, 
a  variation  could  be  produced  by  external  influences  acting  upon 
the  germ-plasm,  understanding  by  external  influences  influences  of 
the  tissue-cells  upon  the  germ-cells,  or,  in  case  the  germ-cells  are 
not  enclosed,  influences  of  the  non-living  environment." 

In  a  recent  exhaustive  paper  by  Tower,  W.  L.,  on  "Evolution  in 
Chrysomelid  beetles  of  the  genus  Leptinotarsa,"  Publication  No.  48 
of  the  Carnegie  Institution  of  Washington,  1907,  the  author,  although 
on  the  whole  a  strong  adherent  of  selection  as  the  all-important 
factor  in  species-forming,  states  specifically  his  belief,  on  the  basis 
of  extensive  observation  and  experiment,  that  external  factors  may 
and  do  influence  the  germ-plasm  to  the  extent  of  compelling  it  to 
produce  variations.  These  variations  will  not  be  photographic  re- 
productions of  modifications  of  the  soma,  but  they  will  be  the  vari- 
,  ations  which  lie  at  the  basis  of  species  change.  In  other  words, 
Tower  holds  that  variations  are  epigenetic  in  their  origin,  although 
they  are  manifest  as  congenital  differences.  That  is,  acquired 
characters  in  the  usual  sense  of  the  term  are  not  heritable,  but  all 
variability  is  nevertheless  due  to  the  influence  of  environment.  This 
paper  by  Tower  is  a  distinctly  valuable  contribution  to  our  knowl- 
edge of  heredity  and  species  change  and  it  is  based  upon  a  large 
amount  of  actual  close  observation  and  experiment. 

In  a  recent  paper  by  Jonathan  Wright,  "The  Origin  and  Heredity 
of  Matter,"  in  the  St.  Louis  Medical  Review,  1906,  something  of  the 
same  attitude  is  taken,  although  the  author  is  much  more  inclined 
to  the  belief  in  the  general  heritability  of  acquired  characteristics. 
This  short  paper  is  an  admirable  treatment,  based  on  a  full  acquaint- 
anceship with  the  modern  literature  on  the  subject,  of  the  problem 
of  heredity. 

8  See  exposition  of  a  number  of  these  theories  in  appendix  of 
chapter  viii  of  this  book. 

4  Haacke,  W.,  "Grundriss  der  Entwicklungsmechanik,"  p.  289 
ff.,  1897- 

8  Plate,  L.,  "Uber  die  Bedeutung  der  Darwin'schen  Selections- 
prinzip,"  p.  218,  1903. 

*  The  following  account  of  the  scientific  aspects  of  Luther  Bur- 


310  DARWINISM   TO-DAY. 

bank's  work,  which  has  attracted  so  much  attention  from  evolu- 
tionists and  the  world  generally,  was  published  by  Kellogg,  in  the 
Pop.  Sci.,  Mo.,  Vol.  LXIX,  pp.  363-374,  1906. 

"Mr.  Burbank  has  so  far  not  formulated  any  new  or  additional 
laws  of  species-change,  nor  do  his  observations  and  results  justify 

Scientific  anv  sucn  formulation,  and  we  may  rest  in  the  belief 

aspects  of  Bur-  that  he  has  no  new  fundamental  laws  to  reveal.  He 
"bank's  work.  jias  indeed  the  right  to  formulate,  if  he  cares  to,  some 
valuable  and  significant  special  conclusions  touching  certain  already 
recognised  evolution  factors,  in  particular  the  influence  on  varia- 
bility of  the  two  long-known  variation-producing  factors  of  hybridi- 
sation and  modification  of  environment.  His  reliance  on  the  marked 
increase  in  variability  to  be  got  after  a  crossing  in  the  second  and 
third  generations  over  that  obvious  in  the  first,  will  come  as  a  sur- 
prise to  most  men  first  getting  acquainted  with  his  work.  He  has 
got  more  starts  for  his  new  things  from  these  generations  than  in 
any  other  way.  He  is  wholly  clear  and  convinced  in  his  own  mind  as 
to  the  inheritance  of  acquired  characters;  'acquired  characters  are 
inherited  or  I  know  nothing  of  plant  life,'  he  says;  and  also  con- 
vinced that  the  only  unit  in  organic  nature  is  the  individual,  not 
the  species;  that  the  so-called  species  are  wholly  mutable  and  de- 
pendent for  their  apparent  fixity  solely  on  the  length  of  time  through 
which  their  so-called  phyletic  characters  have  been  ontogenetically, 
repeated.  He  does  not  agree  at  all  with  de  Vries  that  mutations  in 
plants  occur  only  at  certain  periodic  times  in  the  history  of  the 
species,  but  rather  that,  if  they  occur  at  all,  they  do  so  whenever 
the  special  stimulus  derived  from  unusual  nutrition  or  general 
environment  can  be  brought  to  bear  on  them.  He  finds  in  his 
breeding  work  no  prepotency  of  either  sex  as  such  in  inheritance, 
though  any  character  or  group  of  characters  may  be  prepotent  in 
either  sex.  He  believes  that  no  sharp  line  can  be  drawn  between  the 
fluctuating  or  so-called  Darwinian  variations  and  those  less  usual, 
large,  discontinuous  ones  called  sports.  Ordinary  fluctuating  varia- 
tion goes  on  under  ordinary  conditions  of  nutrition,  but  with  ex- 
traordinary environmental  conditions  come  about  extraordinary 
variation  results,  namely,  discontinuous,  sport  or  mutational  varia- 
tion. These  variations  are  the  effects  of  past  environment  also, 
having  remained  latent  until  opportunity  for  their  development 
occurs.  Starvation  causes  reversions,  but  reversions  can  also  be 
produced  by  unusually  rich  nutrition.  New  variations  are  developed 
most  often,  as  far  as  environmental  influences  go,  by  rich  soil  and 
generally  favourable  conditions.  So-called  new  qualities  are  usually, 
if  not  always  (the  fact  may  sometimes  not  be  obvious),  simply 
new  combinations  of  old  qualities,  both  latent  and  obvious.  To  get 


OTHER   THEORIES   OF   SPECIES-FORMING.        3" 

a  new  and  pleasing  odour  it  may  often  be  sufficient  simply  to  lose 
one  bad  element  in  an  old  odour.  So  one  might  go  on  for  some 
pages  with  specific  conclusions  or  deductions  reached  by  Burbank 
on  a  basis  of  experience.  But  it  is  true  that  he  has  at  his  command 
the  knowledge  of  no  new  fundamental  scientific  principles  to  give  him 
advantage  over  us.  And  yet  none  of  us  has  done  what  Burbank 
has  been  able  to  do,  although  many  of  us  have  tried.  What  then 
is  it  that  Burbank  brings  to  his  work  of  modifying  organisms 
swiftly  and  extremely  and  definitely  that  others  do  not? 

"To  answer  this  it  will  be  advisable  to  analyse  in  general  terms, 
at  least,  the  various  processes  which  either  singly,  or  in  combina- 
tions of  two  or  three,  or  all  together,  are  used  by  Mr.  Burbank  in 
his  work.  We  may  roughly  classify  these  processes  and  means. 
First,  there  is  the  importation  from  foreign  countries,  through 
many  correspondents,  of  a  host  of  various  kinds  of  plants,  some 
of  economic  value  in  their  native  land  and  some  not,  any  of  which 
grown  under  different  conditions  here  may  prove  specially  vigorous 
or  prolific  or  hardy,  or  show  other  desirable  changes  or  new  quali- 
ties. Among  these  importations  are  often  special  kinds  particularly 
sought  for  by  Burbank  to  use  in  his  multiple  hybridisations;  kinds 
closely  related  to  our  native  or  to  already  cultivated  races  which, 
despite  many  worthless  characteristics,  may  possess  one  or  more 
particular,  valuable  ones  needed  to  be  added  to  a  race  already  useful 
to  make  it  more  useful.  Such  an  addition  makes  a  new  race. 

"Second,  the  production  of  variations,  abundant  and  extreme,  by 
various  methods,  as  (a)  the  growing  under  new  and,  usually,  more 
favourable  environment  (food  supply,  water,  temperature,  light, 
space,  etc.)  of  various  wild  or  cultivated  forms,  and  (b)  by  hybridi- 
sations between  forms  closely  related,  less  closely  related  and, 
finally,  as  dissimilar  as  may  be  (not  producing  sterility),  this 
hybridising  being  often  immensely  complicated  by  multiplying 
crosses,  i.  e.,  the  offspring  from  one  cross  being  immediately  crossed 
with  a  third  form,  and  the  offspring  of  this  with  still  another  form, 
and  so  on.  These  hybridisations  are  made  sometimes  with  very 
little  reference  to  the  actual  useful  or  non-useful  characteristics  of 
the  crossed  parents,  with  the  primary  intention  of  producing  an 
unsettling  or  instability  in  the  heredity,  of  causing,  as  Burbank 
sometimes  says,  'perturbations'  in  the  plants,  so  as  to  get  just  as 
wide  and  as  large  variation  as  possible.  Other  crosses  are  made, 
of  course,  in  the  deliberate  attempt  to  blend,  to  mix,  to  add  together, 
two  desirable  characteristics,  each  possessed  by  only  one  of  the 
crossed  forms.  Some  crosses  are  made  in  the  attempt  to  extin- 
guish an  undesirable  characteristic. 

"Third,  there  is  always  immediately  following  the  unusual  produc- 


312  DARWINISM   TO-DAY. 

tion  of  variations,  the  recognition  of  desirable  modifications  and  the 
intelligent  and  effective  selection  of  them,  i.  e.,  the  saving  of  those 
plants  to  produce  seed  or  cuttings  which  show  the  desirable  varia- 
tions and  the  discarding  of  all  the  others.  In  Burbank's  gardens 
the  few  tenderly  cared  for  little  potted  plants  or  carefully  grafted 
seedlings  represent  the  surviving  fittest,  and  the  great  bonfires  of 
scores  of  thousands  of  uprooted  others,  the  unfit,  in  this  close 
mimicry  of  Darwin  and  Spencer's  struggle  and  survival  in  nature. 

"It  is  precisely  in  this  double  process  of  the  recognition  and  selec- 
tion of  desirable  variations  that  Burbank's  'genius  comes  into 
particular  play.  Right  here  he  brings  something  to  bear  on  his 
work  that  few  other  men  have  been  able  to  do.  It  is  the  extraordi- 
nary keenness  of  perception,  the  delicacy  of  recognition  of  desirable 
variations  in  their  (usually)  small  and  to  most  men  imperceptible 
beginnings.  Is  it  a  fragrance  that  is  sought?  To  Burbank  in  a  bed 
of  hundreds  of  seedling  walnuts  scores  of  the  odours  of  the  plant 
kingdom  are  arising  and  mingling  from  the  fresh  green  leaves,  but 
each,  mind  you,  from  a  certain  single  seedling  or  perhaps  from  a 
similar  pair  or  trio.  But  to  me  or  to  you,  until  the  master  prover 
points  out  two  or  three  of  the  more  dominant  single  odours,  the 
impression  on  the  olfactories  is  simply  (or  confusedly)  that  of  one 
soft  elusive  fragrance  of  fresh  green  leaves.  Similarly  Burbank 
is  a  master  at  seeing,  and  a  master  at  feeling.  And  besides  he  has 
his  own  unique  knowledge  of  correlations.  Does  this  plum  seed- 
ling with  its  scores  of  leaves  on  its  thin  stem  have  those  leaves 
infinitesimally  plumper,  smoother  or  stronger,  or  with  more  even 
margins  and  stronger  petiole,  or  what  not  else,'  than  any  other 
among  a  thousand  similar  childish  trees?  Then  it  is  saved,  for 
it  will  bear  a  larger,  or  a  sweeter,  or  a  firmer  sort  of  plum,  or  more 
plums  than  the  others.  So  to  the  bonfires  with  the  others  and  to 
the  company  of  the  elect  with  this  'fittest'  one.  Now  this  recogni- 
tion, this  knowledge  of  correlations  in  plant  structure,  born  of  the 
exercise  of  a  genius  for  perceiving  through  thirty  years  of  oppor- 
tunity for  testing  and  perfecting  it,  is  perhaps  the  most  important 
single  thing  which  Burbank  brings  to  his  work  that  other  men  do 
not  (at  least  in  such  unusual  degree  of  reliability).  Enormous 
industry,  utter  concentration  and  single-mindedness,  deftness  in 
manipulation,  fertility  in  practical  resource,  has  Burbank — and  so 
have  numerous  other  breeders  and  experimenters.  But  in  his  per- 
ception of  variability  in  its  forming,  his  recognition  of  its  possi- 
bilities of  outcome,  and  in  his  scientific  knowledge  of  correlations, 
a  knowledge  that  is  real,  for  it  is  one  that  is  relied  on  and  built  on, 
and  is  at  the  very  foundation  of  his  success,  Burbank  has  an 
advantage  of  true  scientific  character  over  his  fellow  workers,  and 


OTHER   THEORIES   OF   SPECIES-FORMING.       313 

in  it  he  makes  a  genuine  contribution  to  scientific  knowledge  of 
plant  biology,  albeit  this  knowledge  is  so  far  only  proved  to  be 
attainable  and  to  exist.  It  is  not  yet  exposed  in  its  details  and  may 
never  be,  however  unselfish  be  the  owner  of  it.  For  the  going 
to  oblivion  of  scientific  data  of  an  extent  and  value  equivalent,  I 
may  estimate  roughly,  to  those  now  issuing  from  any  half-dozen 
experimental  laboratories  of  variation  and  heredity,  is  the  crying- 
regret  of  all  evolution  students  acquainted  with  the  situation.  The 
recently  assumed  relations  of  Mr.  Burbank  to  the  Carnegie  Insti- 
tution are  our  present  chief  hope  for  at  least  a  lessening  of  this 
loss. 

"But  let  us  follow  our  saved  plum  seedling.  Have  we  now  to 
wait  the  six  or  seven  years  before  a  plum  tree  comes  into  bearing 
to  know  by  actual  seeing  and  testing  what  new  sort  of  plum  we 
have?  No;  and  here  again  is  one  of  Burbank's  contributions  (not 
wholly  original  to  be  sure,  but  original  in  the  extent  and  perfection 
of  its  development)  to  the  scientific  aspects  of  plant-breeding.  This 
saved  seedling  and  other  similar  saved  ones  (for  from  the  exami- 
nation of  20,000  seedlings,  say,  Burbank  will  find  a  few  tens  or 
even  scores  in  which  he  has  faith  of  reward)  will  be  taken  from 
their  plots  and  grafted  on  to  the  sturdy  branches  of  some  full-grown 
vigorous  plum  tree,  so  that  in  the  next  season  or  second  next  our 
seedling  stem  will  bear  its  flowers  and  fruits.  Here  are  years  saved. 
Twenty,  forty,  sixty,  different  seedlings  grafted  on  to  one  strong 
tree  (in  a  particular  instance  Burbank  had  600  plum  grafts  on  a 
single  tree!);  and  each  seedling-stem  certain  to  bear  its  own  kind 
of  leaf  and  flower  and  fruit.  For  we  have  long  known  that  the 
scion  is  not  materially  influenced  by  the  stock  nor  the  stock  by 
the  scion ;  that  is  not  modified  radically,  although  grafting  sometimes 
increases  or  otherwise  modifies  the  vigour  of  growth  and  the  extent 
of  the  root  system  of  the  stock. 

"If  now  the  fruit  from  our  variant  seedling  is  sufficiently  desira- 
ble ;  if  it  produces  earlier  or  later,  sweeter  or  larger,  firmer  or  more 
abundant,  plums,  we  have  a  new  race  of  plums,  a  'new  creation'  to 
go  into  that  thin  catalogue  of  results.  For  by  simply  subdividing 
the  wood  of  the  new  branch,  i.  e.,  making  new  grafts  from  it,  the 
new  plum  can  be  perpetuated  and  increased  at  will.  Simple,  is  it 
not?  No,  it  is  anything  but  that  in  the  reality  of  doing  it;  but  in 
the  scientific  aspects  of  it,  easily  understandable. 

"Perhaps  it  may  not  be  amiss  to  call  attention  to  what  must  be 
the  familar  knowledge  of  most  of  us,  and  that  is  the  fact  that  many 
(probably  most)  cultivated  plants  must  be  reproduced  by  division, 
that  is  by  cuttings,  buds,  or  grafts,  and  not  by  seeds,  in  order  to 
grow  'true.'  For  a  piece  of  a  cultivated  plant  will  grow  out  to  be 


314  DARWINISM   TO-DAY. 

very  much  like  the  individual  it  was  cut  from,  but  the  seeds  will 
not,  in  most  cases,  reproduce  faithfully  the  parents,  but  will  pro- 
duce a  very  variable  lot  of  individuals,  most  of  them  strongly 
reversionary  in  character.  Grow  peach  trees  from  the  stones  of 
your  favourite  peach  and  see  what  manner  of  peaches  you  get ; 
but  if  you  want  to  be  sure  of  more  peaches  like  the  ones  you  enjoy, 
graft  scions  from  your  tree  on  to  other  trees.  Indeed  one  of  the 
plant-breeder's  favourite  methods  of  making  a  start  for  new  things, 
of  getting  the  requisite  beginning  wealth  and  eccentricity  of  varia- 
tion, is  to  grow  seedlings,  especially  from  cross-bred  varieties. 
Burbank  will  give  you  a  thousand  dollars  for  a  pinch  of  horseradish 
seed.  Sugar-cane  seed  is  needed.  The  amelioration  of  many  kinds 
of  fruit  and  flowers  and  vegetables  is  checked,  because  in  our  care- 
lessness we  have  allowed  these  kinds  to  get  into  that  condition  of 
.seedlessness  which  almost  all  cultivated  races  tend  toward  when 
grown  from  cuttings.  In  our  oranges  and  grape-fruit  and  in  a  score 
of  other  fruits,  the  elimination  of  seeds  is  exactly  one  of  the  modifi- 
cations we  have  bred  and  selected  for,  in  order  to  make  the  fruits 
less  troublesome  in  their  eating.  But  when  we  lose  the  seeds 
entirely  of  a  whole  group  of  related  plant  kinds  we  may  find  our- 
selves, as  we  have  found  ourselves  actually  in  many  cases,  at  the 
end  of  our  powers  of  amelioration  of  these  plant  sorts.  Burbank 
believes  that  the  very  fact  that  plants  when  grown  asexually  always 
sooner  or  later  lose  their  power  to  produce  seeds  is  almost  suffi- 
cient proof  (if  such  proof  is  needed)  that  acquired  characters  are 
transmitted. 

"Another  of  Burbank's  open  secrets  of  success  is  the  great  range 
of  his  experimentation — nothing  is  too  bold  for  him  to  attempt, 
the  chances  of  failure  are  never  too  great  to  frighten  him.  And 
another  secret  is  the  great  extent,  as  regards  material  used,  of  each 
experiment.  His  beds  of  seedlings  contain  hundreds,  often  thou- 
sands, of  individuals  where  other  men  are  content  with  hundreds. 
Another  element  in  his  work  is  his  prodigality  of  time.  Experi- 
ments begun  twenty  years  ago  are  actually  still  under  way. 

"In  all  that  I  have  so  far  written,  I  have  purposely  kept  to  gen- 
eral statements  applicable  to  Burbank's  work  as  a  whole.  My 
readers  might  be  more  interested,  perhaps,  to  have  some  illustra- 
tions of  the  application  of  various  processes  of  making  new  sorts 
of  things,  some  analytical  account  of  the  history  of  various  specific 
''new  creations,'  but  considerations  of  space  practically  forbid  this. 
Just  a  few  briefly  described  examples  must  suffice.  More  than  is 
generally  imagined,  perhaps,  Burbank  uses  pure  selection  to  get 
new  things.  From  the  famous  golden  orange  coloured  California 
poppy  (Escholtzia)  he  has  produced  a  fixed  new  crimson  form  by 


OTHER   THEORIES   OF   SPECIES-FORMING.        315 

selection  alone.  That  is,  noticing,  somewhere,  sometime,  an  Escholt- 
£ia  individual  varying  slightly  redder,  he  promptly  took  posses- 
sion of  it,  raised  young  poppies  from  its  seeds,  selected  from  among 
them  those  varying  in  a  similar  direction,  raised  new  generations 
from  them  and  so  on  until  now  he  who  wishes  may  have  his 
California  poppies  of  a  strange  glowing  crimson  for  the  price  of  a 
little  package  of  seed,  where  formerly  he  was  perforce  content 
with  the  golden  orange.  For  me  the  golden  orange  suffices,  but 
that  does  not  detract  from  my  eager  interest  in  the  flower-painting 
methods  of  Mr.  Burbank.  Even  more  striking  a  result  is  his  blue 
Shirley  poppy,  produced  also  solely  by  repeated  selection  from 
the  crimson  field  poppy  of  Europe.  'We  have  long  had  various 
shades  of  black  and  crimson  and  white  poppies,  but  no  shade  of 
blue.  Out  of  200,000  seedlings  I  found  one  showing  a  faintest  trace 
of  sky  blue  and  planted  the  seed  from  it,  and  got  next  year  one 
pretty  blue  one  out  of  many  thousand,  and  now  I  have  one  almost 
pure  blue.' 

"But  another  brilliant  new  poppy  was  made  in  a  different  way. 
The  pollen  of  Papaver  pilosum,  a  butter-coloured  poppy,  was  put 
on  the  pistils  of  the  Bride,  a  common  pure  white  variety  of 
Papaver  somniferum  (double),  and  in  the  progeny  of  this  cross  was 
got  a  fire-coloured  single  form.  The  character  of  singleness  was 
common  to  the  ancestors  of  both  parents,  the  character  of  fire  colour 
in  the  lineage  of  somniferum  only,  although  the  red  of  the  new 
iorm  is  brighter  than  ever  before  known  in  the  somnifera  series. 
Both  characteristics  were  absent  (or  rather  latent)  in  both  parents. 
And  yet  the  perturbing  influence  of  the  hybridisation  brought  to 
the  fore  again  these  ancestral  characters.  The  foliage  of  this  fire 
poppy  is  intermediate  in  type  between  that  of  the  two  parents. 

"The  history  of  the  stoneless  and  seedless  plum,  now  being 
slowly  developed  by  Burbanks,  shows  an  interesting  combination  of 
selection,  hybridisation,  and  reselecting.  Mr.  Burbank  found  a 
plum  in  a  small  wild  plum  species  with  only  a  part  of  a  stone. 
He  crossed  this  wild  species  with  the  French  prune;  in  the  first 
generation  he  got  most  individuals  with  whole  stones,  some  with 
parts  of  a  stone,  and  even  some  with  no  stone.  Through  three 
generations  he  has  now  carried  his  line  by  steadily  selecting,  and 
the  percentage  of  no-stone  fruits  is  slowly  increasing,  while  quality, 
beauty,  and  productiveness  are  also  increasing  at  the  same  time. 

"The  plum-cot  is  the  result  of  crossing  the  Japanese  plum  and  the 
apricot.  The  plum-cot,  however,  has  not  yet  become  a  fixed  variety 
and  may  never  be,  as  it  tends  to  revert  to  the  plum  and  apricot 
about  equally,  although  with  also  a  tendency  to  remain  fixed,  which 
tendency  may  be  made  permanent. 


316  DARWINISM   TO-DAY. 

"Most  of  Burbank's  plums  and  prunes  are  the  result  of  multiple 
crossings  in  which  the  Japanese  plums  have  played  an  important 
part.  Hundreds  of  thousands  of  seedlings  have  been  grown  and 
carefully  worked  over  in  the  twenty  years  of  experimenting  with 
plums,  and  single  trees  have  been  made  to  carry  as  many  as  600 
varying  seedling  grafts.  The  Bartlett  plum,  cross  of  the  bitter 
Chinese  Simoni  and  the  Delaware,  itself  a  Simoni  hybrid,  has  the 
exact  fragrance  and  flavour  of  the  Bartlett  pear.  The  Climax,  a 
successful  shipping  plum,  is  also  a  cross  of  the  Simoni  and  the 
Japanese  triflora.  This  Chinese  Simoni  produces  almost  no  pollen, 
but  few  grains  of  it  ever  having  been  obtained.  But  these  few 
grains  have  enabled  Burbank  to  revolutionise  the  whole  plum 
shipping  industry.  The  sugar  prune,  which  promises  to  supplant 
the  French  prune  in  California,  is  a  selected  product  of  a  second  or 
third  generation  variety  of  the  Petite  d'Agen,  a  somewhat  variable 
French  plum. 

"Next  in  extent  probably  to  Burbank's  work  with  plums  and 
prunes  is  his  long  and  successful  experimentation  with  berries. 
This  has  extended  through  twenty-five  years  of  constant  attention, 
has  involved  the  use,  in  hybridisations,  of  forty  different  species  of 
Rubus,  and  has  resulted  in  the  origination  of  a  score  of  new  com- 
mercial varieties,  mostly  obtained  through  various  hybridisations  of 
dewberries,  blackberries,  and  raspberries.  Among  thes^  may  spe- 
cially be  mentioned  the  Primus,  a  hybrid  of  the  western  dewberry 
(R.  ursinus)  and  the  Siberian  raspberry  (R.  cratagifolius),  fixed 
in  the  first  generation,  which  ripens  its  main  crop  before  most  of 
the  standard  varieties  of  raspberries  and  blackberries  commence  to 
bloom.  In  this  Primus  berry,  we  have  the  exceptional  instance  of 
a  strong  variation,  due  to  hybridisation,  breeding  true  from  the 
time  of  its  first  appearance.  It  usually  takes  about  six  generations 
to  fix  a  new  variety,  but  like  de  Vries's  evening  primrose  mutations, 
the  Primus  berry  is  a  fixed  new  form  from  the  time  of  its  beginning. 
An  interesting  feature  of  Mr.  Burbank's  brief  account,  in  his  'New 
Creations'  catalogue  of  1894,  of  the  berry  experimentation,  is  a  re- 
production of  a  photograph  showing  'a  sample  pile  of  brush,  12 
ft.  wide,  14  ft.  high,  and  22  ft.  long,  containing  65,000  two-  and 
three-year-old  seedling  berry  bushes  (40,000  blackberry  y  rasp- 
berry hybrids  and  25,000  Shaffer  X  Gregg  hybrids)  all  dug  up 
with  their  crop  of  ripening  berries.  The  photograph  is  introduced 
to  give  the  reader  some  idea  of  the  work  necessary  to  produce  a 
satisfactory  new  race  of  berries.  'Of  the  40,000  blackberry  X  rasp- 
berry hybrids  of  this  kind,  "Phenomenal"  is  the  only  one  now  in 
existence.  From  the  other  25,000  hybrids,  two  dozen  bushes  were 
reserved  for  further  trial.' 


OTHER   THEORIES   OF   SPECIES-FORMING.       3J7 

"An  astonishing  result  of  the  hybridisation  between  the  black 
walnut,  Juglans  nigra,  used  as  the  pistillate  parent,  and  the  Cali- 
fornia walnut,  /.  californica,  staminate  parent,  are  walnut  trees 
which  grow  with  such  an  amazing  vigour  and  rapidity  that  they 
increase  in  size  at  least  twice  as  fast  as  the  combined  growth  of 
both  parents.  Many  tremendous  growers  are  got  in  the  first  gen- 
eration, but  in  the  second  there  are  included  some  of  the  most 
rapidly  growing  trees,  perhaps,  in  the  world.  This  hybrid  has 
clean-cut,  glossy  bright-green  leaves  from  two  to  three  feet  long 
with  a  sweet  odour  like  that  of  apples,  but  it  produces  few  nuts. 
Curiously  enough  the  result  of  hybridisation  by  using  the  pollen 
of  nigra  on  pistils  of  californica  produces  in  abundance  large  nuts 
of  a  quality  superior  to  that  possessed  by  either  parent. 

"The  famous  Shasta  daisy  is  the  result  of  a  multiple  crossing 
between  an  American  and  a  European  species  of  field  daisy  and 
then  between  these  hybrids  and  a  Japanese  form.  The  fragrant 
calla,  known  as  'Fragrance/  is  descended  from  a  single  individual 
found  by  Burbank  while  critically  examining  a  block  of  Little  Gem 
calla  seedlings.  He  was  surprised  in  this  examination  by  a  fra- 
grance resembing  that  of  violets  or  water-lilies ;  as  he  had  long 
been  seeking  a  fragrant  calla,  the  individual  giving  this  perfume  was 
carefully  hunted  out.  No  farther  selecting  was  done;  this  plant 
was  the  single  ancestor  of  the  fragrant  new  race. 

"And  so  one  might  go  on  for  pages,  but  with  slight  variations  in 
detail  all  these  pages  would  tell  only  the  same  story :  the  stimulating 
or  inducing  of  variability  by  environmental  influences  and  by  hybrid- 
isations; the  search  after,  and  keen  recognition  of,  promising  spe- 
cial variations ;  the  selection  of  the  plants  showing  these  variations ; 
rearing  new  generations  from  them,  repeated  selection,  and  new 
hybridisations  to  eliminate  this  characteristic  or  introduce  that, 
and  on  until  a  desirable  combination  is  found.  Then  the  careful 
fixing  of  this  form  or  type  by  repeated  selection  through  several 
generations. 

"But  an  end  must  be  made  of  this.  Let  us,  in  a  paragraph,  simply 
sum  up  the  essential  things  in  the  scientific  aspects  of  Burbank's 
work.  No  new.  revelations  to  science  of  an  overturning  character; 
but  the  revelation  of  the  possibilities  of  accomplishment,  based  on 
general  principles  already  known,  by  an  unusual  man.  No  new  laws 
of  evolution,  but  new  facts,  new  data,  new  canons  for  special  cases. 
No  new  principle  or  process  to  substitute  for  selection,*  but  a  new 
proof  of  the  possibilities  of  the  effectiveness  of  the  old  principle. 
No  new  categories  of  variations,  but  an  illuminating  demonstration 
of  the  possibilities  of  stimulating  variability  and  of  the  reality  of 
this  general  variability  as  the  fundamental  transforming  factor. 


3*8  DARWINISM   TO-DAY. 

No  new  evidence  either  to  help  the  Darwinian  factors  to  their  death- 
bed, or  to  strengthen  their  lease  on  life;  for  the  'man'  factor  in  all 
the  selecting  phenomena  in  Burbank's  gardens  excludes  all  'natural' 
factors.  Here  are  some  of  Burbank's  own  words,  touching  these 
matters  that  scientific  men  are  particularly  interested  in,  in  his  work : 

"  'All  scientists  have  found  that  preconceived  notions,  dogmas, 
and  all  personal  prejudice  must  be  set  aside,  listening  patiently, 
quietly,  and  reverently  to  the  lessons  one  by  one  which  mother 
nature  has  to  teach,  shedding  light  on  that  which  before  was  a 
mystery,  so  that  all  who  will  may  see  and  know. 

"  'Crossing  gives  the  raiser  of  new  plants  the  only  means  of 
uniting  the  best  qualities  of  each,  but  just  as  often  the  worst  quali- 
ties of  each  are  combined  and  transmitted,  so  that  to  be  of  any 
value  it  must  be  followed  by  rigid  and  persistent  selection,  and  in 
crossing,  as  in  budding  and  grafting,  the  affinities  can  only  be 
demonstrated  by  actual  test. 

"  'All  wild  plants  of  any  species  are  under  almost  identical  envi- 
ronments, having  their  energies  taxed  to  the  utmost  in  the  fierce 
struggle  for  existence.  Any  great  variation  under  such  circum- 
stances is  not  likely  to  occur,  and  is  much  more  likely  to  be  stamped 
out  at  once  by  its  struggling  competitors,  unless  the  variation  should 
be  of  special  use  in  competition,  in  which  case  it  will  survive,  and 
all  others  may  be  supplanted  by  it.  Thus  we  see  how  new  species 
are  often  produced  by  nature,  but  this  is  not  her  only  mode.  Crosses 
and  hybrids  are  very  often  found  growing  wild  where  two  some- 
what similar  species  grow  contiguous,  and  if  the  combination  hap- 
pens to  be  a  useful  one,  as  it  often  does,  the  new  creation  is 
encouraged  by  nature ;  then  time  and  environment  fix  it,  and  man 
comes  on  the  scene,  perhaps  ages  later,  and  discovers  it,  and,  not 
knowing  all  the  facts,  wonders  where  the  connecting  links  have 
gone.  It  is  botanically  classified  as  a  new  species,  which  it  is  most 
certainly. 

"  'In  cultivated  plants  the  life  struggle  is  removed,  and  here  we 
find  variation  almost  the  rule  rather  than  the  exception. 

"  'Varieties  are  the  product  of  fixed  laws,  never  of  chance,  and 
with  a  knowledge  of  these  laws  we  can  improve  the  products  of 
nature,  by  employing  nature's  forces,  in  ameliorating  old  and  produc- 
ing new  species  and  varieties  better  adapted  to  our  necessities  and 
tastes.  Better  food,  more  sunshine,  less  arduous  competition,  will 
of  themselves  induce  variation  in  individual  plants  which  will  be 
more  or  less  transmitted  to  their  seedlings,  which,  selected  con- 
secutively through  a  certain  number  of  generations,  will  become 
permanent.  Environment  here  exerts  an  influence  as  in  all  chemical 
cosmical,  and  celestial  movements.  These  small  increments  from 


OTHER   THEORIES   OF   SPECIES-FORMING. 

environmental  forces  may  produce  a  gradual  or  sudden  change 
according  to  circumstances.  The  combustion  of  food  liberates  the 
moving  force,  environment  guides  it  as  it  does  the  planets. 

"  'When  once  the  persistent  type  is  broken  up,  old  latent  forces 
may  be  liberated  and  types  buried  in  the  dim  past  reappear.  This, 
called  atavism,  is  a  concentration  of  ancestral  forces — reverberating 
echoes — from  varieties  long  since  passed  away,  exhibiting  them- 
selves when  from  some  cause,  for  instance  crossing,  present  forces 
are  in  a  state  of  antagonism,  division,  perturbation,  or  weakness. 
These  echoes,  if  collected  by  crossing  and  selection,  produce  com- 
binations of  superlative  importance  and  value.'  " 

7  Plate,  L.,  "Uber  die  Bedeutung,"  etc.,  p.  220. 

8  See  Koken,   Ernst,  "Palseontologie  und  Descendenzlehre,"   1902. 
Koken   (Professor  of  Geology  and  Palaeontology  in  the  University 

Orthogenetic  °f  Tubingen)  is  very  explicit  in  the  statements  of  his 
variation  in  belief  that  the  palaeontological  records  prove  the  exist- 
paleontology,  ence  of  orthogenetic  variation  and  hence  evolution. 
"Das  Darwin'sche  Prinzip  der  Selektion  ist  nicht  das  einzige,  das. 
in  Betracht  kommt  und  es  scheint  nicht  das  wichtigste  zu  sein. 
Vielfach  vermissen  wir  in  der  palseontologischen  Geschichte  den 
Hinweis  auf  ein  Eingreifen  des  Kampfes  urns  Dasein  und  anderer- 
seits  heben  sich  Richtungen  der  Entwickelung  herans.  welche  nicht 
in  Beziehung  zu  einem  Nutzen  stehen,  in  einigen  Fallen  zu  einer 
Schadigung  der  socialen  Bedingungen  fiihren." 

9  For  an  account  of  the  facts  of  one  such  case,  see  Kellogg,  "Is-. 
There  Determinate  Variation,"  Science,  N.  S.,  Vol.  XXIV,  pp.  621- 
628,    1906.     In    this    paper    the    gradual    but    obvious    change    from. 

A  case  of  ap-  one  dominant  type  of  colour-pattern  to  another  in 
parent  determi-  the  leaf-eating  beetle  Diabrotica  soror  (on  the  campus, 
nate  variation,  of  Stanford  University,  California)  during  the  last, 
ten  years,  is  shown  by  statistical  variation  studies.  It  is  shown 
that  such  change  is  not  explicable  on  a  basis  of  intra-specific 
selection,  nor  can  it  be  interpreted  as  a  direct  ontogenic  reaction 
in  each  succeeding  generation  to  changing  climatic  conditions.  The 
case  is  believed  to  be  an  example  of  definitive  orthogenetic: 
variation. 

Certain  examples  of  presumable  determinate  variation  have  been, 
recorded  by  Henslow  ("The  Origin  of  Species,"  Natural  Science, 
p.  259,  1894).  "In  1847,  Prof.  J.  Buckman  sowed,  seed  of  wild 
parsnip  in  the  garden  of  the  Agricultural  College,  at  Cirencester. 
The  seedlings  began  to  vary,  but  in  the  same  way,  though  in  differ- 
ent degrees.  By  selecting  seed  from  the  best  rooted  plants,  the 
acquired  'somatic'  characters  of  .an  enlarged  root,  glabrous  leaves, 
etc.,  became  fixed  and  hereditary;  and  'The  Student,'  as  he  calledi 


320  DARWINISM   TO-DAY. 

it,  having  been  'improved'  by  Messrs.  Sutton  &  Sons,  is  still 
regarded  as  'the  best  in  the  trade.'  This  is  definite  variation,  ac- 
cording to  Darwin's  definition,  for  those  weeded  out  did  not  differ 
from  the  selected,  morphologically,  except  in  degree,  the  variations 
towards  improvement  not  being  quite  fast  enough  to  entitle  them 
to  survive. 

"M.  Carriere  raised  the  radish  of  cultivation,  Raphanus  sativus, 
L,.,  from  the  wild  species  R.  raphanistum,  L.,  and  moreover  found 
that  the  turnip-rooted  form  resulted  from  growing  it  in  a  heavy 
soil,  and  the  long-rooted  one  in  a  light  soil.*  Pliny  records  the 
.same  fact  as  practised  in  Greece  in  his  day,  saying  that  the  'male' 
(turnip  form)  could  be  produced  from  the  'female'  (long  form),  by 
growing  it  in  'a  cloggy  soil.'  Both  forms  are  now,  of  course, 
hereditary  by  seed." 

10  Nageli,   C.   von,    "Mechanisch-physiologische   Theorie   der   Ab- 
stammungslehre,"  1884. 

11  Korschinsky,    S.,    "Heterogenesis    und    Evolution,"    Naturwiss. 
Wochenschrift,  Vol.  XIV,  pp.  273-278,  1899. 

12  Recently,   Georg  Pfeffer    ("Die   Entwicklung,"   1895)    has  pro- 
posed a  theory  of  orthogenetic  evolution  not  very  different   from 

the  much  earlier  Nagelian  one.  Pfeffer  postulates  as 
of  ortho'enesis1^  mnerent  *n  living  matter  a  capacity  for  change  and 
for  self-directing  this  change.  The  principle  of 
change  or  progress  he  calls  the  conception  of  "developmental-screw" 
(Entwicklungsschraube) ,  and  for  directing  this  progress  the  con- 
ception of  "self-steering"  (Selbststeuerung).  Both  these  capacities 
of  individualised  living  stuff  are  something  over  and  beyond  the 
mechanical  and  physico-chemical  attributes  of  living  matter.  "On 
the  contrary,"  says  Pfeffer,  "life  consists  of  the  capacity  (more 
exactly  the  exercise  of  this  capacity)  of  consciously  permitting  and 
consciously  influencing  (that  is,  actually  producing)  through 
physico-chemical  phenomena  changes  in  the  matter  or  form  of  the 
fundamental  life-stuff." 

From  this  curious,  though  keen,  critical,  and  constructive  essay, 
I  quote  as  follows : 

"Der  Begriff  der  Entwickelungsschraube  deckt  sich  eigentlich 
vollig  mit  dem  Begriff  der  Selbststeuerung  der  lebendigen  Natur; 
ich  halte  aber  mit  gutem  Grunde  beide  Ausdriicke  aufrecht,  weil 
sie  einer  verschiedenen  Betrachtung  entspringen,  namlich  die 
Selbststeuerung  der  mechanischen,  die  Entwickelungsschraube  der 
historischen,  entwickelungsgeschichtlichen  Betrachttmgsweise ;  die 
Selbststeuerung  ist  das  Prinzip  der  Herstellung  des  Gleichgewichtes 

*  This  has  been  corroborated  by  M.  Languet  with  the  carrot.  Soc. 
Roy.  et  Cent.  d'Agricult.,  2d  ser.,  Vol.  II,  1846-7,  p.  539. 


OTHER   THEORIES   OF   SPECIES-FORMING.        321 

eines  aus  lebendigen  Einheiten  gebildeten  Ganzen ;  die  Entwickel- 
ungsschraube  das  Prinzip  der  veranderten  Weiterfiihrung  dieser 
Gleichgewichtsverhaltnisse  in  der  Zeit  Also  ist,  ebenso  wie  die 
Selbststeuerung,  auch  die  Entwickelungsschraube  selbstthatig  (pp. 
12  and  13). 

"Es  ist  hier  nicht  der  Ort,  die  physikalischen  wie  die  Unzahl  der 
chemischen  Eigenschaften  der  lebendigen  Grundsubstanz  zu  eror- 
tern;  sie  liegen  freilich  nicht  auf  der  Hand,  sind  aber  im  Ganzen 
ziemlich  leicht  herzuleiten  als  das  alien  lebendigen  protoplasmati- 
schen  Substanzen  Gemeinsame.  Es  fallt  aber  Niemandem  ein,  bez. 
sollte  Niemandem  einfallen,  die  physikalischen  und  chemischen 
Eigenschaften  der  lebendigen  Substanz  als  Lebens-Eigenschaften  zu 
betrachten;  vielmehr  besteht  das  Leben  in  der  Fahigkeit  (bez.  der 
Ausiibung  der  Fahigkeit),  die  durch  chemisch-physikalische 
Vorgange  an  dem  Stoff  oder  der  Form-Auspragung  der  Grund- 
substanz bewirkten  Veranderungen  bewusst  zu  erleiden  und  bewusst 
zu  beeinflussen  (bez.  hervor  zu  bringen).  Es  hat  also  jeder  kor- 
perliche  Vorgang  der  lebendigen  Substanz  seinen  von  ihm  untrenn- 
baren  Bewusstseinsvorgang ;  oder  anders  ausgedriickt :  jeder  Vor- 
gang an  lebendigen  Wesen  hat  einen  in  chemisch-physikalische  und 
einen  anderen  in  Bewusstseins-Verhaltnisse  zerlegbaren  Anteil. 
Beide  sind  Gegenstande  wissenschaftlicher  Betrachtung,  dagegen 
entzieht  sich  die  Art  und  Weise  des  Zusammenhanges  zwischen 
beiden  unserm  Anschauungsvermogen,  liegt  also  ausserhalb  der 
naturwissenschaftlichen  Betrachtung  und  ist  damit  als  gegeben 
hinzunehmen"  (p.  17). 

A  recent  proposal  of  an  orthogenetic  theory  of  the  general 
character  of  Nageli's  is  that  set  out  in  O.  F.  Cook's  "Aspects  of 
Kinetic  Evolution,"  Proc.  Wash.  Acad.  Sci.,  Vol.  VIII,  pp.  197-403, 
1907. 

13  Eimer,  Th.,  "Die  Entstehung  der  Arten  auf  Grund  von  Verer- 
bung  erworbener  Eigenschaften  nach  den  Gesetzen  organischen 
Wachsens,"  I,  1888;  trans,  into  English,  as  "Organic 
oforSfogenesTs!7  Evolution,"  1889;  "Artbildung  und  Verwandschaft 
bei  den  Schmetterlingen,"  I,  1889,  II,  1895;  "Ortho- 
genesis bei  Schmetterlinge"  (Part  II  of  "Die  Entstehung  der 
Arten"),  1898;  "Orthogenesis,"  3  Internat.  Congress  Zool.,  1895; 
trans,  in  English  as  "On  Orthogenesis  and  the  Impotence  of  Natural 
Selection  in  Species-Formation,"  1898.  This  address,  and  Eimer's 
other  writings  as  well,  are  sadly  marred  by  intemperate  polemic 
and  the  indulgence  of  personal  rancor.  He  deems  himself  and  his 
views  unfairly  overlooked  by  biologists  and  seems  to  hold  Weismann 
personally  responsible  for  this.  Apart  from  these  unfortunate 
digressions  his  papers  are  extremely  suggestive  and  logically  and 


322  DARWINISM   TO-DAY. 

keenly  composed.  I  believe  that  Eimer's  work  and  theories  should 
have  more  attention  from  students  of  evolution  then  they  now  get. 

14  Dean,  Bashford.  "Evolution  in  a  Determinate  Line,  as  Illus- 
trated by  the  Egg-Cases  of  Chimaeroid  Fishes,"  Biol  Bull.,  Vol. 
Apparent  deter- VII,  pp.  105-112,  1904.  In  this  paper  the  author 
minate  evolution,  expresses  his  belief  that  the  conditions  existing  in  the 
curious  inter-related  adaptations  between  eggs  and  egg-cases  of  the 
shark-like  fish,  Chimaera,  can  be  explained  only  on  the  basis  of 
determinate  or  orthogenetic  modifications,  in  which  modifications 
neither  natural  selection  nor  the  Lamarckian  factors  of  use  and 
disuse  can  have  played  any  part.  The  capsule  or  egg-case,  although 
"only  indirectly  connected  with  the  egg,  i.e.,  as  a  secretion  formed 
by  the  parent  after  the  mechanism  of  heredity  has  already  been 
established  in  the  egg,  nevertheless  foresees  with  startling  exact- 
ness the  size  and  shape  of  the  young  fish  when  many  months  hence 
it  comes  to  hatch  out,  and  it  provides  a  series  of  progressive  multi- 
plications adapted  to  the  physical  needs  of  the  young.  It  is  evident, 
accordingly,  that  if  natural  selection  be  adduced  to  explain  the 
present  phenomena  it  encounters  difficulties  more  numerous  and 
complex  than  in  usual  instances.  In  the  latter  cases  selection  con-1 
cerns  itself  with  variations  which  affect  the  progeny  directly;  but 
in  the  present  case  variations  must  have  occurred  in  the  lines  both 
of  the  progeny  and,  indirectly,  of  its  far  less  indifferent  capsule- 
forming  capabilities — with  result  that  a  succession  of  closely  corre- 
lated stages  in  variation  must  have  coincided  in  both  distinct  con- 
ceptions." 

16  Plate,  L.,  "Uber  die  Bedeutung,"  etc.,  p.  190  ff. 

16  Rosa,  Daniel,  "La  Riduziorie  Progressiva  della  Variabilita  i 
suoi  Rapporti  coll'  Estinzione  e  coll'  Origine  della  Specie,"  1899. 
Author  believes  that  in  animal  life  there  is  a  gradual  progressive 
reduction  of  variation  (or  modification)  necessitated  by  the  well- 
known  fact  that  highly  specialised  forms  have  distinctly  fewer  lines 
of  modification,  i.  e.  specialisation,  left  open  to  them  than  general- 
ised forms;  and  that  all  groups  of  animals  are  of  the  nature  of 
series  of  more  and  more  specialised  forms.  He  bases  this  belief,  as 
far  as  facts  go,  on  the  well-known  cases  of  the  dying  out  of  spe- 
cialised species  (Irish  stag)  and  specialised  groups  (Cretaceous 
reptiles),  and  on  the  alleged  facts  (which  the  author  devotes  many 
pages  to  trying  to  show)  that  all  present-day  principal  groups  of 
animals  are  related  to  each  other  solely  by  derivation  from  com- 
mon very  old  and  generalised  ancestors.  If  there  is  less  modifica- 
tion possible,  then  there  occurs  actually  less  and  less  variability,  and 
the  actually  occurring  variations  will  be  only  along  certain  lines, 
i.  e.  there  will  be  in  this  limited  variability  an  actual  basis  for  ortho- 


OTHER   THEORIES   OF   SPECIES-FORMING.        323 

genesis.  On  the  double  basis  of  progressively  less  variation  and  of 
the  thus  produced  orthogenesis  the  author  sees  a  factor  in  phylogeny 
(organic  evolution)  which  works,  to  some  degree,  independently  of 
natural  selection  or  of  Lamarckian  factors.  Rosa  thinks  he  has 
thus  contributed  to  biology  one  of  the  always  sought-for  "unknown 
factors  in  evolution." 

17  In  an  interesting  paper  by  Snodgrass,  "The  Relation  of  the  Food 
to  the  Size  and  Shape  of  the  Bill  in  the  Galapagos  Genus  Geospiza," 

Snodgrass's  Auk,  Vol.  XIX,  pp.  367-381,  IQO2,  detailing  the  ex- 
observations  on  amination  of  the  stomach  contents  of  over  200  indi- 
billsofGala-  viduals,  representing  13  species  and  sub-species  (taken 
pagos  ir  s.  from  several  of  the  Galapagos  Islands)  of  the  peculiar 
Galapagos  Fringillid  genus,  Geospiza,  remarkable  for  the  great 
differences  in  size  and  shape  of  bill  characterising  the  various 
species  and  sub-species,  the  author  states  that  all  the  "evidence 
seems  to  be  in  favour  of  the  general  conclusion  that  there  is  no 
correlation  between  the  food  and  the  size  and  shape  of  the  bill." 
The  following  five  propositions  were  established:  (i)  The  same 
species  at  different  localities  may  feed  on  different  seeds;  (2) 
different  species  at  the  same  locality  may  feed  on  the  same  kinds 
of  seeds;  (3)  different  species  at  different  localities  may  feed  on 
the  same  kinds  of  seeds;  (4)  different  species  at  the  same  or  at 
different  localities  may  feed  on  different  seeds;  and  (5)  birds 
with  small  bills  eat  only  small  seeds ;  birds  with  large  bills  eat  both 
small  and  large  seeds.  The  seeds  taken  from  the  stomachs  varied 
in  size  from  seeds  of  I  cubic  millimetre  up  to  those  15  mm.  long 
by  10  mm.  thick.  The  bill  of  the  different  species  and  sub-species 
of  Geospiza,  varies  from  that  of  G.  scandens  scandens,  13  mm. 
long  by  7  mm.  high  at  base,  to  that  of  G.  pachyrhyncha,  17  mm. 
long  by  20  mm.  high  at  base. 

18  Eimer,  Th.,  "Orthogenesis  der  Schmetterlinge,"  1897. 

19  Cope,    E.    D.,   "The   Method   of   Creation   of   Organic   Types," 
Proc.  Amer.  Phil.  Soc.,  December,  1871. 

20  Cope,  E.  D.,  "The  Energy  of  Life  Evolution,"  Pop.  Sci.  Mo., 
Vol.    XXVII,    pp.    789-800,    October,    1885:    "Primary    Factors    of 
Organic  Evolution,"  1896. 

21  "Palaeontologists,  as  a  rule, — and  Prof.  Cope  is  one  of  them, — 
are  so  profoundly  impressed  by  the  adaptive  nature  of  the  evolu- 

Oope's  belief  tionary  process  and  by  the  definitiveness  of  its  direc- 
in  orthogenetic  tion,  that  they  cannot  regard  the  restraining  or 
evolution.  selective  action  of  the  environment  as  enough  to  keep 

the  breed  true.  They  are  so  accustomed  to  seeing  mutation,  after 
mutation,  generation  after  generation,  developing  in  apparent  obe- 
dience to  obvious  physico-chemical  or  mechanical  conditions,  that 


324  DARWINISM   TO-DAY. 

they  incline  to  regard  these  conditions  as  causes.  And  if  it  be 
suggested  to  them  that  the  results  they  see  may  have  been  achieved 
by  the  selection  of  adaptive  variations  from  among  a  number  of 
promiscuous  variations  that  are  not  adaptive,  they  ask  why  it  is 
that  they  do  not  find  evidence  of  these  numerous  known  adaptive 
variations  in  the  organs,  when  one  would  suppose  that,  on  any 
hypothesis,  except  that  of  definite  variation,  such  forms  must  have 
been  the  more  abundant  of  the  two.  It  is  useless  to  reply  to  them 
that  the  known  adaptive  variations  in  each  generation  were  killed  off 
when  young,  and  so,  even  if  fossilised,  are  practically  undistinguish- 
able;  because  they  will  reply  with  abundant  proof  that  the  adaptive 
characters  chiefly  appear  in  the  adult  stages  of  the  organism,  possibly 
only  in  its  senile  stages,  and  so  are  incapable  of  coming  under 
the  action  of  natural  selection  during  the  early  undifferentiated 
stages.  How  the  conversation  might  continue  does  not  much 
matter,  for  it  is  obvious  that  it  has  reached  a  point  beyond  which  all 
must  be  speculation.  The  facts  on  which  the  palaeontologist  relies, 
the  facts  that  Prof.  Cope  adduces  with  such  wealth  of  knowl- 
edge, are  strong  presumptive  evidence  in  favour  of  his  second 
thesis,  but  they  are  not  proof."  (Bather,  F.  A.,  Natural  Science, 
Vol.  X,  pp.  40-41,  1897.) 

Prof.  Scott,  another  American  palaeontologist,  discusses  the 
question  of  variation  in  an  interesting  paper  in  the  American  Journal 
of  Science,  Vol.  XLVIII,  pp.  335-374,  1894.  The  great  point  made 
by  Prof.  Scott  is  the  clear  distinction  between  individual  and 
phylogenetic  variation.  Individual  variation  is  irregular  and  not 
fixed,  while  "phylogenetic  variation,"  or  mutation  (in  the  sense  of 
*  Waagen)  which  is  distinguished  from  individual  variation,  not 
by  any  character  of  quantity  or  quality,  but  by  pursuing  a  deter- 
minate direction  and  thus,  under  control  of  natural  selection,  leading 
to  the  formation  of  new  species.  "Remembering  that  the  signifi- 
cant fact  in  the  history  of  a  group  is  not  so  much  the  character  of 
its  variations  at  any  one  stage,  as  the  gradually  shifting  positions 
successively  occupied  by  the  normal  or  centre  of  stability,  we  find 
that  any  mammalian  series  at  all  complete,  such  as  that  of  the 
horses,  is  remarkably  continuous,  and  that  the  progress  of  discovery 
is  steadily  filling  up  what  few  gaps  remain.  So  closely  do  successive 
stages  follow  upon  one  another  that  it  is  sometimes  extremely 

*  The  term  "mutation"  was  first  used  in  biology,  probably,  by 
Waagen,  1869,  in  a  paper  on  the  phylogeny  of  an  ammonite.  In 
this  first  use  of  the  word  its  meaning  was  a  change  or  modification 
accomplished  during  a  considerable  historic  period.  Indeed,  it  had 
much  the  meaning  of  evolution  or  descent  as  we  use  these  terms 
nowadays. 


OTHER   THEORIES   OF   SPECIES-FORMING.        325 

difficult  to  arrange  them  all  in  order  and  to  distinguish  clearly 
those  members  which  belong  in  the  main  line  of  descent,  and  those 
which  represent  incipient  branches.  Some  phylogenies  actually 
suffer  from  an  embarrassment  of  riches." 

22  Whitman,  C.  O.,  "The  Problem  of  the  Origin  of  Species,"  Pro- 
ceedings of  Congress  of  Arts  and  Science,  Universal  Exposition,  St. 

Whitman's  Louis,  Vol.  V,  pp.  41-58,  1906.  In  this  paper  Whit- 
belief  in  deter-  man  takes  strong  ground  for  orthogenesis  and  recites 
minate  variation.  jn  detail  a  number  of  interesting  facts  touching  the 
evolution  of  pattern  in  pigeons  to  illustrate  his  belief.  Touching 
the  criticism  of  orthogenesis,  that  it  involves  a  teleologic  element 
in  its  make-up,  Whitman  says  (p.  5)  :  "I  take  exception  here  only 
to  the  implication  that  a  definite  variation-tendency  must  be  con- 
sidered to  be  teleologic  because  it  is  not  'orderless.'  I  venture  to 
assert  that  variation  is  sometimes  orderly,  and  at  other  times  rather 
disorderly,  and  that  the  one  is  just  as  free  from  teleology  as  the 
other.  In  our  aversion  to  the  old  teleology  so  effectually  banished 
from  science  by  Darwin  we  should  not  forget  that  the  world  is 
full  of  order,  the  inorganic  no  less  than  the  organic.  Indeed,  what 
is  the  whole  development  of  an  organism  if  not  strictly  and  marvel- 
lously orderly?  Is  not  every  stage,  from  the  primordial  germ  on- 
ward, and  the  whole  sequence  of  stages,  rigidly  orthogenetic?  If 
variations  are  deviations  in  the  directions  of  the  developmental 
processes,  what  wonder  is  there  if  in  some  directions  there  is  less 
resistance  to  variation  than  in  others?  What  wonder  if  the  organ- 
ism is  so  balanced  as  to  permit  of  both  unifarious  and  multifarious 
variations?  If  a  developmental  process  may  run  on  throughout 
life  (e.  g.,  the  life-long  multiplication  of  the  surface-pores  of  the 
lateral-line  system  in  Amia),  what  wonder  if  we  find  the  whole 
species  gravitating  slowly  in  one  or  a  few  directions?  And  if 
we  find  large  groups  of  species,  all  affected  by  a  light  variation, 
moving  in  the  same  general  direction,  are  we  compelled  to  regard 
such  'a  definite  variation-tendency'  as  teleological,  and  hence  out 
of  the  pale  of  science?  If  a  designer  sets  limits  to  variation  in 
order  to  reach  a  definite  end,  the  direction  of  events  is  teleological ; 
but  if  organisation  and  the  laws  of  development  exclude  some 
lines  of  variation  and  favour  others,  there  is  certainly  nothing  super- 
natural in  this,  and  nothing  which  is  incompatible  with  natural 
selection.  Natural  selection  may  enter  at  any  stage  of  ortho- 
genetic  variation,  preserve  and  modify  in  various  directions  the 
results  over  which  it  may  have  had  no  previous  control." 

28  Cunningham,  an  English  neo-Lamarckian,  expresses  ("Origin 
of  Species  Among  Flatfishes,"  Natural  Science,  Vol.  VI,  p.  239, 
1895)  his  belief  in  orthogenesis  as  follows: 


326  DARWINISM   TO-DAY. 

"The  only  general  view,  as  it  seems  to  me,  which  can  be  held 
concerning  the  structural  diversity  of  the  animal  kingdom,  is  to 
regard  it  as  resultant  of  two  more  or  less  opposing 
Cunningham  generai  tendencies.  On  the  one  hand,  there  is  uni- 
8<  versal  evidence  of  a  tendency  to  definite  variation,  or 
growth  in  different  directions,  leading  to  manifold  variety  of  regu- 
lar definite  symmetrical  forms.  This  tendency  can  only  be  regarded 
as  internal  to  the  organism,  as  connected  with  a  tendency  to  growth 
and  multiplication  inherent  in  organic  units.  On  the  other  hand, 
there  is  the  molding,  limiting,  constructing  action  of  the  external 
forces  of  the  environment  resulting  in  more  or  less  complete  adap- 
tation. Whatever  be  the  process  of  adaptation,  whether  Darwinian 
selection  or  Lamarckian  modification,  adaptive  structural  combina- 
tions are  mechanisms  each  working  with  the  particular  result  which 
is  important  to  the  feeding,  living,  and  breeding  of  the  organism. 
Whatever  the  causes  of  non-adaptive  variation,  the  resulting  struct- 
ural features  are  the  regular  genetic  forms  and  characters  which  the 
multitude  of  different  organic  forms  present  in  such  marvellous 
diversity.  No  one  who,  like  Weismann,  ignores  everything  except 
adaptation,  or  who,  like  Bateson,  regards  the  study  of  adaptations 
as  barren  and  profitless,  can  hope  to  produce  a  consistent  and  com- 
prehensive theory  of  organic  evolution." 

24  Delage,  Yves,  "L'Heredite,"  2d  ed.  p.  849,  and  others,  1903. 

25  Jaeckel,   O.,   "Uber  verschiedene   Wege   phylogenetischer   Ent- 
wicklung,"   1902. 


CHAPTER  XL 

OTHER  THEORIES  OF  SPECIES-FORMING  AND 
DESCENT  (  CONTINUED  ) :  ALTERNATIVE 
THEORIES  (CONTINUED). 

Hetero genesis. — Under  the  name  heterogenesis  we  have 
to  consider  a  theory  of  species-forming  which  is  more  popu- 
larly and  widely  known  under  another  name,  viz.,  the  muta- 
tions theory.  This  theory  is  commonly  associated  with  the 
name  of  de  Vries,  the  Amsterdam  botanist.  But  this  gen- 
eral conception  of  species-forming  on  a  basis  of  the  occur- 
rence of  occasional,  sudden,  fixed,  and  often  considerable 
changes  or  variations  in  the  offspring  of  a  plant  or  animal, 
is  a  conception  not  of  course  new  with  de  Vries,  but  one 
variously  expressed  by  numerous  biologists  from  Dar- 
win's time  on,  especially  by  von  Kolliker,  Galton,  Dall, 
Bateson,  Emery,  Scott,  and  Korschinsky.  It  is,  however, 
•chiefly  due  to  the  patient,  persistent,  well-planned,  and  ex- 
tensive experiments  and  observations  of  de  Vries  that  this 
theory  of  species-forming  by  heterogenesis,  or  as  called  by 
de  Vries,  by  mutations,  has  recently  received  so  much  re- 
newed attention.  With  the  observations  of  de  Vries  on  the 
breeding  of  certain  plant  species,  notably  certain  CEhotheras 
(evening  primroses),  there  have  been  much  associated  in 
recent  popular  scientific  literature  accounts  of  the  ear- 
lier observations  of  Gregor  Mendel,1  an  Augustinian  monk, 
who  recorded,  in  1865,  in  an  obscure  journal,  some  very 
valuable  observations  and  logical  conclusions  concerning  the 
phenomena  of  heredity  in  certain  other  plants  (especially 
garden  peas).  Reference  should  also  be  made,  in  this  con- 

327 


328  DARWINISM   TO-DAY. 

nection,  to  observations  and  experiments  carried  on  nearly 
simultaneously  with  those  of  de  Vries  by  Correns  2  and 
Tschermak.3  As  a  matter  of  fact  the  data  on  which  de 
Vries  bases  his  theory  of  species-forming  by  heterogenesis 
are,  in  part,  nearly  identical  with  those  obtained  by  Mendel, 
Tschermak,  and  Correns,  which,  however,  is  concerned 
primarily  with  explaining  the  "laws"  of  heredity. 

The  meaning  of  heterogenesis  in  connection  with  species- 
forming  and  descent  is  essentially  this :  whereas  by  the 
Darwinian  theory  species  are  transformed  slowly  and  by 
slight  changes  in  at  first  one  or  two  or  a  few  and  only 
later  in  more  parts,  and  all  new  species  are  derived  from  the 
old  ones  (which  usually  disappear  as  the  new  ones  appear) 
by  the  gradual  selection  of  the  advantageous  ones  among  the 
regular  slight,  fluctuating,  individual  variations  (known 
commonly  as  Darwinian  variations  and  which  mostly  occur 
according  to  the  law  of  error),  by  the  theory  of  hetero- 
genesis new  species  appear  suddenly,  not  by  a  selective 
choosing  among  the  slight  fluctuating  Darwinian  variations, 
but  independently  of  selection,  and  largely  independently  of 
the  so-called  Darwinian  variations,  by  the  appearance  in 
fixed  definitive  form  of  several  to  many  slight  to  consider- 
able variations,  which  give  the  new  species  definite  char- 
acteristics differentiating  it  often  in  many  particulars  from 
the  old  species,  which  differentiating  characteristics  are  fully 
and  faithfully  transmitted  to  the  succeeding  generations  of 
individuals  derived  from  this  suddenly  born  new  species. 

In  some  theories  or  views  of  heterogenesis  the  suddenly 

appearing  new  variations — and  none  of  these  theories  gives 

a  satisfactory  explanation  of  the  cause  of  these 

Discontinuous    sllcjden    variations— which    give    rise    to    new 
variation. 

species,  are  those  large,  sometimes  monstrous, 

variations  known  as  "sports,"  "monsters,"  etc. ;  or,  in  Bate- 
son's  words,  are  "discontinuous  variations,"  i.  e.,  considerable 
variations  not  connected  by  a  continuous  series  of  gradations. 


OTHER   THEORIES   OF   SPECIES-FORMING.        329 

with  the  parent  type  of  the  variable  organ  or  individual. 
Darwinians  have  always  been  interested  in  such  variations, 
for  if  they  do  occur  in  any  considerable  numbers  they  might 
offer  a  possible  solution  of  that  difficulty  in  the  selection 
theory  of  explaining  the  origin  of  new  structures  and  the 
needed  degree  of  size  and  development  sufficient  to  make 
these  beginnings  useful  and  hence  available  as  handles  for 
natural  selection.  But  it  has  long  been  recognised  that  such 
sports  or  discontinuous  variations  are  too  few  and  occur  too 
rarely  to  furnish  the  basis  for  a  comprehensive  theory  of 
species-forming.  Like  the  extremes  of  individuals  in  the 
series  of  fluctuating  variations,  their  characters  would  be 
lost  or  swamped  by  crossing.  Darwin  himself  made  as  full 
a  list  of  such  sports  as  any  post-Darwinian  writer,  ex- 
cepting Bateson,  has  been  able  to  do,  and  he  recognised 
the  fact  that  certain  species,  or  races  at  least,  of  domesticated 
animals  and  cultivated  plants  undoubtedly  had  their  begin- 
nings in  these  sports.  His  examples  of  such  discontinuous 
or  saltatory  evolution  as  the  Ancon  and  Mauchamp  sheep, 
the  Paraguay  cattle,4  etc.,  are  the  classic  examples  in  ani- 
mal evolution,  and  to  this  day  nearly  the  only  ones !  Bate- 
son  c  has,  to  be  sure,  gathered  together  in  his  "Materials 
for  the  Study  of  Variation"  a  much  larger  list  of  sports  or 
discontinuous  variations  than  Darwin  included  in  his  knowl- 
edge (it  should  be  borne  in  mind  in  referring  to  Bateson's 
list  that  several,  probably,  indeed,  many  of  his  alleged  ex- 
amples are  cases  of  teratogenic  regeneration) — but  he  has 
been  able  to  add  almost  no  new  examples  of  the  origin  of 
a  new  species  from  such  discontinuous  variations.  A  few 
cases  are  known  of  the  inheritance  through  a  number  of 
generations  of  suddenly  appearing  sports  or  discontinuous 
variations  in  human  beings  (cases  of  polydactyly,  etc.)  and 
cats.  (Kennel's  stump-tailed  cat,  which  produced  in  six 
litters  four  stump-tailed,  twelve  tailless,  and  twelve  normal 
young,  is  an  example  of  several  similar  cases  which  have 


330  DARWINISM   TO-DAY. 

been  recorded.)  Species-forming  by  sports  and  discon- 
tinuous variations  is  obviously  no  theory  to  presume  to 
offer  itself  as  a  species-forming  substitute  for  natural  selec- 
tion. But  the  de  Vriesian  mutations  theory,  the  most 
recent  development  of  the  heterogenesis  conception,  has 
rehabilitated  this  conception  to  such  an  extent  that  a  number 
of  biologists  see  in  it  an  actually  satisfactory  substitute  for 
the  natural  selection  theory.  Before  explaining  the  theory 
of  de  Vries  let  us  first  note  two  or  three  other  prior  formula- 
tions of  theories  of  heterogenesis,  one  at  least  being  nearly 
identical  with  that  of  de  Vries. 

In  1864  the  great  zoologist  von  Kolliker,9  in  a  paper  under 

the  title  "t)ber  die  darwinische    Schopfungstheorie,"  took 

positive  ground  against  the  adequacy  or  actuality 

VonE.olhker's  Q£  naturai  selection  as  a  species- forming  factor, 

suggestion,  r  D 

and  proposed  a  theory  of  "heterogene  Erzeu- 
gung"  (heterogenesis)  which  he  formulated,  however,  only 
in  most  general  terms.  He  said  that  "under  the  influence 
of  a  general  law  of  development  (evolution)  organisms 
bring  forth  other  kinds  differing  from  them  out  of  the 
germs  produced  by  them."  He  included  in  his  general  theory 
of  heterogenesis  a  basic  plan  of  progressive  evolution. 
Such  a  conception  has  in  it  too  much  autogenic  orthogenesis ; 
it  is  too  redolent  of  teleology  for  present-day  biology.  The 
variations,  too,  which  are  to  serve  as  beginnings  of  new 
species  are  those  too  rare  ones  which  we  have  referred  to 
as  sports  and  discontinuous  variations. 

The  American   naturalist,   Dall,T   in  a  paper   written   in 
1877,    expresses    his    conviction    that    sudden    changes    of 

species-forming  character   do   occur,    and   as- 

Dall's  belief      cribes    such    changes    "to    the    action    of    the 

iies-chang^6"      ^aw    of   development,    which    finds    expression 

in  the  paradox  that  the  same  species  may 
belong  to  different  genera."  That  sudden  leaps  may  be 
due  to  the  gradual  accumulation  of  minute  differences  he 


OTHER   THEORIES   OF    SPECIES-FORMING.        33* 

exemplifies  as  follows:  "In  a  sloping  gutter  of  a  paved 
street  not  too  cleanly  swept  every  one  will  notice  on  a  sudden 
shower  how  small  particles  of  earth  and  other  materials 
will  sometimes  act  as  a  dam,  producing  a  puddle  which, 
relieved  by  partial  draining,  may  for  a  time  remain  in 
statu  quo.  A  time  comes,  however,  when  the  gradually 
accumulated  pressure  suddenly  sweeps  the  dam  before  it 
for  a  short  distance,  until  another  similar  one  is  formed,  the 
pool  again  appears  for  a  time  to  remain  unchanged,  and 
so  on  indefinitely.  Now  the  modern  idea  of  a  species  may  be 
stated  to  be  a  greater  or  lesser  number  of  similar  individual 
organisms  in  which  for  the  time  being  the  majority  of 
characters  are  in  a  condition  of  more  or  less  stable  equi- 
librium, and  which  have  the  power  to  transmit  these  char- 
acters to  their  progeny  with  a  tendency  to  maintain  this 
equilibrium.  This  tendency  may  be,  in  some  cases,  sufficiently 
strong  to  resist  for  a  considerable  period  the  changes  which 
a  gradual  modification  of  the  environment  may  tend  to  bring 
about.  When  the  latter  has  reached  a  pitch  which  renders 
the  resistance  no  longer  effectual,  it  is  conceivable  that  a 
sudden  change  may  take  place  in  the  arrangement  of  the 
constitution  of  the  organism,  adapting  it  once  more  to  its 
surroundings,  when  the  tendency  to  equilibrium  may  reassert 
itself  in  the  minor  characteristics,  and  they  may,  as  it  were, 
crystallise  once  more  in  a  form  not  dissimilar  in  generic 
type.  If  among  a  certain  assemblage  of  individuals  con- 
stituting a  species,  the  tendency  to  maintain  the  specific 
equilibrium  be  (as  it  should  be  a  priori)  transmitted  to  the 
progeny  in  different  degrees  of  intensity,  a  gradual  separa- 
tion might  take  place  between  those  with  a  stronger 
tendency  to  equilibrium  and  those  with  less.  Here  natural 
selection  would  come  in.  Those  yielding  as  above  to  the 
pressure  of  the  environment  would  necessarily  become  better 
adapted  to  it  (or  perish)  and  with  their  changed  generic 
structure  might  be  able  to  persist.  On  the  other  hand,  those 


332  DARWINISM   TO-DAY. 

with  the  broader  base,  so  to  speak,  with  the  inherited 
tendency  to  remain  unshaken  by  the  modifications  of  the 
environment,  may  be  conceived  as  through  this  tendency 
to  be  and  to  remain  less  injuriously  affected  by  adverse 
circumstances,  and  consequently  might  still  endure.  In 
short,  natural  selection  in  the  one  case  would  find  its  ful- 
crum in  the  tendency  to  easy  adjustment  of  characters ;  and 
in  the  other  case  in  the  inherited  persistency  in  equilibrium 
rendering  its  possessor  more  or  less  indifferent  to  the  in- 
jurious elements  of  the  environment.  The  intermediate 
individuals  by  the  hypothesis  would  be  those  least-fitted  to 
persist  in  any  case  and  hence  liable  to  be  rapidly  eliminated. 
Then  we  should  have  parallel  series  of  species  in  two  or  even 
more  genera  existing  simultaneously." 

Francis  Galton,  the  great  student  of  heredity  and,  in  most 

of  his  belief  a  thorough  Darwinian,  nevertheless  held  it  to  be 

probable  that  evolution  might  proceed  not  only 

Walton's  belief  by  minute  steps  but  that  decisive  sudden  changes 
in  discontinuous       r     ,  ,<rr(1         ,. 

stepgi  of  the  type  may  occur.       That  the  steps  may 

be  small  and  that  they  must  be  small  are  very 
different  views ;  it  is  only  to  the  latter  that  I  object,  and 
only  when  the  indefinite  word  'small'  is  used  in  the  sense  of 
'barely  discernible'  or  as  small  compared  with  such  large 
sports  as  are  known  to  have  been  the  origin  of  new  races."  ' 
And  his  familiar  analogy  of  organic  stability  to  that  of  the 
polygon  9  with  unequal  sides,  whose  stability  or  fixity  de- 
pends upon  which  of  these  sides  it  may  be  resting  on,  ex- 
presses well  the  basic  idea  in  heterogenesis  or  mutation  by 
small  but  definitive  and  fairly  stable  changes.  Galton  also 
believed  in  the  stability  or  fixity  of  sports ;  not  that  all  trans- 
mit their  character  to  their  young  but  that  many  do  and  thus 
give  rise  to  new  types. 

Emery,10  in  his  suggestive  paper  called  "Gedanken  zur 
Descendenz-  und  Vererbungstheorie,"  expresses  his  belief 
in  the  importance  in  species-forming  of  what  he  calls  "pri- 


OTHER   THEORIES   OF   SPECIES-FORMING.        333 

mary  variations,"  which  are  large  and  sudden  as  contrasted 
with   "secondary  variations,"   which   are   the   usual    small, 
,  fluctuating  or  so-called   Darwinian  variations, 

ory  of  "primary  Emery  bases  his  belief  on  the  few  cases  like 
variations,"  ^  ^ncon  sheep  and  the  inherited  six-fingered- 
ness  of  men,  and  also  on  an  argument  drawn  from  the  dif- 
ficulty of  explaining  by  the  natural  selection  theory  various 
-existing  conditions  such  as  sexual  polymorphism,  and  numer- 
ous cases  of  extremely  complex  structural  and  physiological 
specialisation.  But  there  is  little  that  is  convincing  in 
Emery's  presentation. 

A  later  exponent  of  heterogenesis  of  a  different  kind,  and 

a  more  sharply-spoken  antagonist  of  the  selection  theory, 

much  more  nearly  anticipates  de  Vries's  muta- 

Korscliinsky's 

theory  of  hetero-  tion  theory.  Indeed  this  biologist,  the  Russian 
botanist  Korschinsky,  in  his  championship  of 
heterogenesis  goes  much  beyond  de  Vries  in  his  denial  of  the 
influence  of  selection  in  species-forming  and  descent.  De 
Vries,  as  we  shall  see,  admits  natural  selection  to  be  a  factor, 
and  perhaps  a  large  one  in  the  determination  of  descent,  of 
organic  evolution,  but  holds  it  to  be  wholly  a  restraining  and 
cutting-back  factor,  not  at  all  a  formative  one.  Korschinsky 
says  plainly  that  the  struggle  for  existence  and  selection 
have  either  no  influence  in  species-forming  and  descent,  or, 
if  any,  a  hindering  and  antagonising  influence,  a  retarding 
and  nullifying  influence.  Korschinsky  has  published  his 
theory  in  three  papers,  one  a  large  work  in  Russian  which  I 
have  not  seen,  the  others  shorter  papers  ll  in  German  which 
are  of  the  nature  of  vorlailfige  Mitteilungen.  In  these 
papers  he  formulates  clearly  and  positively  a  theory  of 
heterogenesis  or  species-forming  by  "mutations"  and  attacks 
sharply  and  positively  the  natural  selection  theory.  A  con- 
cise statement  of  his  theory  and  at  the  same  time  of  his 
position  with  regard  to  the  selection  theory  is  given  by 
him  in  a  table  of  two  columns  in  which  the  contrast  between 


334 


DARWINISM   TO-DAY. 


the  two  theories  is  graphically  shown.     I  translate  here  this 
"parallel  columns"  statement  in  full : 


ACCORDING     TO    THE    TRANSMUTA- 
TION  THEORY. 

1.  To  all  organisms  there  be- 
longs   a    capacity    for    variation 
which  is  called  into  play  partly 
through    inner,    partly    through 
outer    causes,    through   use    and 
disuse,    etc.      This    capacity    for 
variation  regularly  finds  its  ex- 
pression   in    the    appearance    of 
slight  and  unnoticeable  individ- 
ual differences. 

2.  As  a  result   of  this   strug- 
gle  for   existence  and   selection, 
those      individual      variations 
which    prove   themselves    useful 
become   fixed   and   accumulated, 
while   the   non-useful   ones   dis- 
appear.    All   characteristics  and 
peculiarities    of   a    species   must, 
as  a  result  of  a  prolonged  selec- 
tion, stand  in  harmony  with  the 
outer  conditions,  and  be  useful 
to  the  organism. 

3.  Through    prolonged    selec- 
tion and   accumulation  of  char- 
acteristics   all    species    undergo 
a     persistent     change,     whereby 
they   are   gradually   transformed 
into  new  species  without,  how- 
ever,   sacrificing     their     normal 
physiological  relations. 


4.  This  process  can  take  place 
everywhere  and  under  all  cir- 
cumstances. The  harder  the 
outer  conditions  and  the  sharp- 
er the  struggle  for  existence, 
the  more  energetically  selection 
works,  and  therewith  the  quick- 


ACCORDING     TO     THE     THEORY     OF 
HETEROGENESIS. 

1.  To  all  organisms  there  be- 
longs   a    capacity    for    variation, 
which    is    a    fundamental    inner 
peculiarity  independent  of  outer 
conditions,    and    which    remains 
usually   in   latent  condition,   re- 
tained   by    heredity,    but    which 
now  and  then  finds  its  expres- 
sion in  sudden  changes. 

2.  These  sudden  changes  can, 
under  favourable  conditions,  be 
the     beginnings     of     persistent 
races.      These    new    characteris- 
tics, having  appeared  independ- 
ently   of    outer    conditions,    are 
sometimes  useful  to  the  organ- 
ism, but  they  may  also  stand  in 
no   harmony  with   outer   condi- 
tions. 


3.  All  once-formed  species  re- 
main  unchanged,    although   new 
forms  occasionally  split  off  from 
them    by    heterogenesis.      Such 
newly-arisen  forms  have,  as  the 
result  of  a  disturbed  heredity,  a 
deranged  constitution,  which  re- 
veals itself  in  a  lessened  fertility 
and  often  in  a  generally  weak- 
ened condition  of  the  organism. 
The  new  forms,  becoming  con- 
stant   races,    gradually    recover 
their  constitution. 

4.  The    origin    of   new    forms 
can,  however,  occur  only  under 
favourable   conditions    of   exist- 
ence   for    the    species,    and    the 
more    favourable    these    condi- 
tions,   that    is,    the    less    severe 
the    struggle    for   existence,    the 


OTHER   THEORIES   OF   SPECIES-FORMING.        335 


er     the     development     of     new 
forms. 


5.  The  chief  requisite  for  evo- 
lution is,  therefore,  the  struggle 
for  existence  and  the  selection 
which  results  from  it. 


6.  If  there   were  no   struggle 
for    existence,    no    selection,    no 
survival  of  the  strongest,  there 
would  be   no  evolution   and  no 
specialisation,    for   adapted    spe- 
cies  would   have   no    advantage 
over  unadapted  ones,  and  as  a 
result  of  crossing  with  the  lat- 
ter,   they    would    sacrifice    their 
useful  characteristics. 

7.  The    so-called    advance    in 
nature  or  the  perfecting  of  or- 
ganisms, is  nothing  else  than  a 
more    complex,    more    complete 
adaptation    to   outer   conditions, 
and    it    is    reached    in    a    purely 
mechanical    way   through    selec- 
tion   and    the    accumulation    of 
characteristics  useful   under  the 
existent  outer  conditions. 


more  energetically  can  evolution 
go  on.  New  forms  do  not  arise 
under  hard  external  conditions, 
or  if  any  do,  they  go  quickly  to 
ground. 

5.  The  struggle  for  existence, 
and  the  selection  that  goes  hand 
in  hand  with  it,  constitute  a  fac- 
tor which  limits  new  forms  and 
hinders  further  variation  and  is, 
therefore,  in  no  way  favourable 
to  the  origin  of  new  forms.     It 
is  a  factor  inimical  to  evolution. 

6.  If   there    were    no    struggle 
for  existence,  there  would  be  no 
killing  out  of  newly  arising  or  al- 
ready arisen  forms.     The  world 
of  organisms  could  then  grow  to 
a   mighty   tree,   whose   branches 
could   all   persist   in   blossoming 
condition,  and  the  most  aberrant, 
now   isolated,   species   would   be 
connected  with  all  others  through 
intermediate  forms. 

7.  The     adaptation     which 
comes     to     exist     through     the 
struggle  for  existence  is  not  at 
all  identical  with  an  advance,  for 
higher,    more    specialised    (voll- 
kommenere)    forms    are    by    no- 
means  always  better  adapted  to 
outer  conditions  than  the  lower 
ones.     One   cannot   explain   the 
evolution     of    organisms    in     a 
purely  mechanical   way.     In  or- 
der   to    explain    the    origin    of 
higher  forms  out  of  lower  it  is 
necessary    to    admit    a     special 
tendency,  in  organisms,  for  ad- 
vance,   which    is    nearly    related 
to,   or   identical   with   the   tend- 
ency to   vary,   and   which   com- 
pels  organisms   toward  perfect- 
ness  as  far  as  external  conditions 
allow. 


The  theory  of  heterogenesis  as  formulated  by  Korschinsky 
(and  also  as  held  by  de  Vries,  as  we  shall  see)  is  not  neces- 


336  DARWINISM   TO-DAY. 

sarily  a  theory  of  sudden  large  changes  or  variations,  al- 
though it  is  of  sudden  and  fixed  ones.  It  is  not  based  on 
any  belief  that  sports  or  large  variations  are  any  more 
numerous,  nor  of  any  more  worth  as  the  beginnings  of  new 
species,  than  now  generally  recognised,  but  it  assumes 
sudden  radical  changes  in  the  organism  which,  if  not  visibly 
large  as  regards  obvious  quantitative  conditions,  are  large  or 
at  least  comprehensive  as  regards  qualitative  conditions. 
The  mutation  or  variation  assumed  by  the  theory  of  hetero- 
genesis affects  many  organs  and  parts,  structurally  and 
physiologically ;  it  produces  a  radical  change  throughout  the 
organism.  And  this  change  is  the  result  of  an  influence 
wholly  intrinsic,  inherent,  and  has  no  reference  to  external 
conditions,  except  in  that  the  stimulus  for  it  may  come  partly 
or  chiefly  from  specially  favourable  conditions  of  nutrition. 
This  change  is  at  once  definitive  and  fixed :  it  is  transmitted 
unimpaired  to  the  offspring  of  the  organism  showing  the 
mutation,  only  the  capacity  for  the  production  of  offspring, 
i.  e.,  the  reproductive  fertility,  is  often  weakened. 

Korschinsky's  theory  and  declarations  are  not  based  on 
any  very  large  amount  of  personal  experimentation  and 
observation — at  least  his  references  to  new  facts  are  few  and 
meagre.  He  gives  a  short  list  of  old  and  more  or  less 
familiar  together  with  a  few  new  examples  of  heterogenesis 
but  he  does  not  lend  the  theory  of  heterogenesis  very  much 
in  the  way  of  authority,  except  in  so  far  as  the  evidently 
positive  and  clear  conviction  on  the  part  of  a  biologist  of 
experience  and  reputable  standing  of  the  necessity  and  truth 
of  such  a  theory  is  authority.  Korschinsky's  conviction  is 
probably  based  on  much  observation  and  experience  besides 
that  which  he  definitely  catalogued,  but  what  is  needed  to 
carry  conviction  to  others  is  direct  reference  to  proved,  and 
where  possible  verifiable,  facts  of  observation  and  experi- 
ment. 

The  supplying  of  this  demand,  to  a  degree  which  will 


OTHER   THEORIES   OF    SPECIES-FORMING.        337 

appear  to  various  people  insufficient  or  sufficient  according 

to  their  respective  ideas  of  what  is  needed  in 

De  Vries  and    the  way  of  fact  material  for  the  satisfactory 

themutations        founding    of    a    theory>    k    ig    the    spedal    yir_ 

tue  of  de  Vries  to  have  attempted  on  behalf 
of  heterogenesis. 

De  Vries  12  introduces  his  now  classic  two-volume  pres- 
entation of  his  views  on  evolution  and  species-forming 
("Die  Mutationstheorie,"  1901-1903)  with  the  following 
paragraph : 

"Als  Mutationstheorie  bezeichne  ich  den  Satz,  dass  die 
Eigenschaften  der  Organismen  aus  scharf  von  einander 
unterschiedenen  Einheiten  aufgebaut  sind.  Diese  Einheiten 
konnen  zu  Gruppen  verbunden  sein,  und  in  verwandten 
Arten  kehren  dieselben  Einheiten  und  Gruppen  wieder. 
Ubergange,  wie  sie  uns  die  ausseren  Formen  der  Pflanzen 
und  Thiere  so  zahlreich  darbieten,  giebt  es  aber  zwischen 
diesen  Einheiten  ebensowenig,  wie  zwischen  den  Molekiilen 
der  Chemie."  And  again  in  the  first  paragraph  of  the 
preface  to  his  book  "Species  and  Varieties"'8  (an  edited 
transcription  of  his  American  lectures  on  species-forming, 
delivered  in  California  in  1904)  he  says :  ".  .  .  but  the 
way  in  which  one  species  originates  from  another  has  not 
been  adequately  explained.  The  current  belief  assumes  that 
species  are  slowly  changed  into  new  types.  In  contradic- 
tion to  this  conception  the  theory  of  mutation  assumes  that 
new  species  and  varieties  are  produced  from  existing  forms 
by  sudden  leaps.  The  parent-type  itself  remains  unchanged 
throughout  this  process,  and  may  repeatedly  give  birth  to 
new  forms.  These  may  arise  simultaneously  and  in  groups, 
or  separately  at  more  or  less  widely  distributed  periods." 

Obviously  there  is  no  ambiguity  here  as  to  the  relation 
of  species-forming  by  mutation  to  species-forming  by 
gradual  modification  through  selection  or  fluctuating  varia- 
tions. In  the  words  of.  de  Vries :  "Species  have  not  arisen 


338  DARWINISM   TO-DAY. 

through  gradual  selection  continued  for  hundreds  or  thou- 
sands of  years,  but  by  jumps  (stufenweise)  through  sudden, 
though  small,  transformations.  In  contrast  with  variations 
which  are  changes  in  a  linear  direction  the  transformations 
to  be  called  mutations  constitute  divergence  in  new  directions. 
They  take  place,  so  far  as  experience  goes,  without  definite 
direction."  14  And  even  if  transition  forms  exist  between 
the  species  produced  by  mutations,  they  are  no  evidence 
against  the  mutations,  "for,"  says  de  Vries,  "the  transitions 
do  not  appear  before  the  new  species,  at  most  only  simul- 
taneously with  this,  and  generally  only  after  this  is  already 
in  existence.  The  transitions  are  therefore  no  intermediates 
or  preparations  for  the  appearance  of  the  new  forms.  The 
origin  takes  place,  not  through  them,  but  wholly  independ- 
ently of  them."  16 

Too  often  de  Vries's  theory  is  said  not  to  be  alternative 
with  Darwin's,  but  auxiliary  to  it.  As  regards  the  forma- 
tion of  new  species,  the  two  theories  are  directly 
De  Vries's  in  opposition.  But  as  regards  the  general 
opposition  to  course  of  organic  evolution  (which  is  another 
Darwin's  as  con-  matter)  the  mutations  theory  is  not  in  contra- 
forming^"  diction  to  the  theory  of  descent  through 
selection.  De  Vries  himself  says :  "Notwith- 
standing all  these  apparently  unsurmountable  difficulties, 
Darwin  discovered  the  great  principle  which  rules  the  evolu- 
tion of  organisms.  It  is  the  principle  of  natural  selection. 
It  is  the  sifting  out  of  all  organisms  of  minor  worth  through 
the  struggle  for  life.  It  is  only  a  sieve,  and  not  a  force  of 
nature,  no  direct  cause  of  improvement,  as  many  of  Dar- 
win's adversaries,  and  unfortunately  many  of  his  followers 
also,  have  so  often  asserted.  It  is  only  a  sieve,  which  de- 
cides which  is  to  live,  and  what  is  to  die.  But  evolutionary 
lines  are  of  great  length,  and  the  evolution  of  a  flower  or 
of  an  insectivorous  plant  is  a  way  with  many  side-paths.  It 
is  the  sieve  that  keeps  evolution  on  the  main  line,  killing 


OTHER   THEORIES   OF   SPECIES-FORMING.        339 

all  or  nearly  ail  that  try  to  go  in  other  directions.  By  this 
means  natural  selection  is  the  one  directing  cause  of  the 
broad  lines  of  evolution." 

While  de  Vries  admits  that  recorded  mutations  are  few ; 
"mutations  under  observation  are  as  yet  very  rare;  enough 
to  indicate  the  possible  and  most  probable  ways  but  no 
more;"  17  yet  he  strongly  maintains  that  there  is  no  scientific 
proof  of  the  origin  of  species  in  any  other  way  than  by 
mutation  and  that  there  is  such  proof  of  their  actual  muta- 
tional  origin.  He  says :  "I  intend  to  give  a  review  of  the 
facts  obtained  from  plants  which  go  to  prove  the  assertion 
that  species  and  varieties  have  originated  by  mutation  and 
are,  at  present,  not  known  to  originate  in  another  way." 

But  in  any  consideration  of  de  Vries's  work  and  theories, 
one  must  have  clearly  in  mind  the  distinctive  meaning 
which  de  Vries  attaches  to  the  word  species.  However 
little  biologists  agree  on  any  absolute  definition  of  species, 
the  term  nevertheless  is  consistently  used  to  refer  to  differ- 
entiated organic  types  between  any  two  of  which  there  is 
considerable  obvious  describable  difference,  either  quali- 
tative or  quantitative.  If  two  types  of  such  obvious  differ- 
ence in  one  or  several  characteristics  (usually  external  or 
at  least  externally  noticeable  differences  are  the  ones  used) 
are  connected  by  a  series  of  connecting  gradatory  forms 
existing  either  in  the  same  territory  or  in  other  regions,  the 
two  forms  are  not  referred  to  as  distinct  species  but  as 
varieties ;  at  least  the  form  at  one  end  of  the  series  is  called 
a  variety  of  the  form  at  the  other  end.  But  de  Vries's 
species  and  varieties  are  of  different  stuff.  Specific  dis- 
tinctions with  him  are  based  on  differences  in  aggregation 
of  the  elementary  units,  the  Einheiten,  that  go  to  compose 
the  specific  types.  "Species  is  a  word,"  says  de  Vries, 
"which  always  has  had  a  double  meaning.  One  of  them  is 
the  systematic  species,  which  is  the  unit  of  our  system. 
But  these  units  are  not  at  all  indivisible.  Long  ago  Lin- 


340  DARWINISM   TO-DAY. 

nseus  knew  them  to  be  compound  ideas  in  a  great  number 
of  instances,  and  increasing  knowledge  has  shown  that  the 
same  rule  prevails  in  other  instances.  To-day  the  vast  ma- 
jority of  the  old  systematic  species  are  known  to  consist  of 
minor  units.  These  minor  entities  are  called  varieties  in  sys- 
tematic works.  However,  there  are  many  objections  to  this 
usage.  First,  the  term  variety  is  applied  in  horticulture  and 
agriculture  to  things  so  widely  divergent  as  to  convey  no 
clear  idea  at  all.  Secondly,  the  subdivisions  of  species  are 
by  no  means  all  of  the  same  nature,  and  the  systematic 
varieties  include  units  the  real  value  of  which  is  widely 
different  in  different  cases.  Some  of  these  varieties  are  in 
reality  as  good  as  species,  and  have  been  'elevated,'  as  it  is 
called,  by  some  writers,  to  this  rank.  This  conception  of  the 
elementary  species  would  be  quite  justifiable,  and  would  at 
once  get  rid  of  all  difficulties,  were  it  not  for  one  practical 
obstacle.  The  number  of  the  species  in  all  genera  would  be 
doubled  and  tripled,  and  as  these  numbers  are  already 
cumbersome  in  many  cases,  the  distinction  of  the  native 
species  of  any  given  country  would  lose  most  of  its  charm 
and  interest. 

"In  order  to  meet  this  difficulty  we  must  recognise  two 
sorts  of  species.  The  systematic  species  are  the  practical 
units  of  the  systematists  and  florists,  and  all  friends  of  wild 
nature  should  do  their  utmost  to  preserve  them  as  Linnaeus 
has  proposed  them.  These  units,  however,  are  not  really 
existing  entities;  they  have  as  little  claim  to  be  regarded 
as  such  as  the  genera  and  families  have.  The  real  units 
are  the  elementary  species ;  their  limits  often  apparently 
overlap  and  can  only  in  rare  cases  be  determined  on  the 
sole  ground  of  field-observations.  Pedigree-culture  is  the 
method  required  and  any  form  which  remains  constant  and 
distinct  from  its  allies  in  the  garden  is  to  be  considered  as 
an  elementary  species." 

With  regard  to  varieties  de  Vries  has  the  following  to 


OTHER   THEORIES   OF   SPECIES-FORMING.       34* 

say :  "Linnaeus  himself  knew  that  in  some  cases  all  sub- 
divisions of  a  species  are  of  equal  rank,  together  constituting 
the  group  called  species.  No  one  of  them  outranks  the 
others;  it  is  not  a  species  with  varieties,  but  a  group  con- 
sisting only  of  varieties.  A  closer  inquiry  into  the  cases 
treated  in  this  manner  by  the  great  master  of  systematic 
science  shows  that  here  his  varieties  were  exactly  what  we 
now  call 'elementary  species. 

"In  other  cases  the  varieties  are  of  a  derivative  nature. 
The  species  constitutes  a  type  that  is  pure  in  a  race  which 
ordinarily  is  still  growing  somewhere,  though  in  some  cases 
it  may  have  died  out.  From  this  type  the  varieties  are 
derived,  and  the  way  of  this  derivation  is  usually  quite 
manifest  to  the  botanist.  It  is  ordinarily  by  the  disappear- 
ance of  some  superficial  character  that  a  variety  is  dis- 
tinguished from  its  species,  as  by  the  lack  of  colour  in  the 
flowers,  of  hairs  on  stems  and  foliage,  of  the  spines  and 
thorns,  etc.  Such  varieties  are,  strictly  speaking,  not  to  be 
treated  in  the  same  way  as  elementary  species,  though  they 
often  are.  We  shall  designate  them  by  the  term  of  'retro- 
grade varieties,'  which  clearly  indicates  the  nature  of  their 
relationship  to  the  species  from  which  they  are  assumed  to 
have  sprung.  In  order  to  lay  more  stress  on  the  contrast 
between  elementary  species  and  retrograde  varieties,  it 
should  be  stated  at  once,  that  the  first  are  considered  to 
have  originated  from  their  parent-form  in  a  progressive 
way.  They  have  succeeded  in  attaining  something  quite 
new  for  themselves,  while  retrograde  varieties  have  only 
thrown  off  some  peculiarity,  previously  acquired  by  their 
ancestors."  19 

With  regard  to  the  facts  and  general  evidence  20  on  which 

The  facts  at      ^e  ^ries  ^ases  ms  beliefs  and  theory  a  few 

basis  of  de          words,  too  few,  I  regret,  must  suffice.      Like 

Vries's  theory,      Darwin>    de   yries    only   came   to   the    full   pub. 

lication  of  his  theory  after  many  years  of  assiduous  obser- 


342  DARWINISM   TO-DAY. 

vation,  of  persistent  compilation  of  other  men's  observing, 
and  careful  weighing  and  consideration  of  the  data  in 
hand.  In  de  Vries's  case  too  there  was  added  a  large 
amount  of  experimental  testing  of  his  conclusions.  This 
experimental  study  of  the  species-forming  problem  de 
Vries  and  his  followers  rather  seem  to  claim  as  a  distinct- 
ively new  part  of  the  basis  for  the  mutations  theory,  but  as 
a  matter  of  fact  Darwin  himself,  in  much  less  degree  per- 
haps, and  in  somewhat  different  manner,  appealed  to  experi- 
ment to  test  many  of  his  conclusions.  The  actual  forming 
of  new  species  by  selection  could  not  be  experimentally 
tested  or  proven  by  Darwin.  Whether  biologists  are  ready 
to  accept  de  Vries's  pedigree-culture  work  and  results  as 
of  the  same  nature  of  rigid  experimental  test  and  proof  as 
there  exists  in  experimentation  in  chemistry  and  static 
physics  (for  that  is  the  claim  for  the  new  "experimental 
method"  in  biology)  remains,  perhaps,  a  moot  point.  De 
Vries's  general  statement  of  the  character  and  the  amount 
of  the  evidence  on  which  he  rests  his  belief  in  the  formation 
of  species  by  mutation  is  contained  in  the  following  para- 
graphs from  his  book  "Species  and  Varieties"  (p.  22). 

"Mutations  are  occurring  from  time  to  time  in  the  wild 
state  as  well  as  in  horticulture  and  agriculture.  A  selec- 
tion of  the  most  interesting  instances  will  be  given  later. 
But  in  all  such  cases  the  experimental  proof  is  wanting. 
The  observations,  as  a  rule,  only  began  when  the  mutation 
made  its  appearance.  A  more  or  less  vague  remembrance 
about  the  previous  state  of  the  plants  in  question  might  be 
available,  though  even  this  is  generally  absent.  But  on 
doubtful  points  concerning  possible  crosses  or  possible  intro- 
duction of  foreign  strains,  mere  recollection  is  insufficient. 
The  fact  of  the  mutation  may  be  very  probable,  but  the  full 
proof  is,  of  course,  wanting.  Such  is  the  case  with  the 
mutative  origin  of  Xanthium  commune  Wootoni  from  New 
Mexico  and  of  (Enothera  biennis  cruciata  from  Holland. 


OTHER   THEORIES   OF   SPECIES-FORMING.        343 

The  same  doubt  exists  as  to  the  origin  of  the  Capsella 
Heegeri  of  Solms-Laubach,  and  of  the  oldest  recorded  muta- 
tion, that  of  Chelidonium  laciniatum  in  Heidelberg  about 
1600." 

Next,  after  introducing  the  necessity  of  experimental 
proof  and  explaining  how  one  must  go  to  work  to  acquire 
such  proof  he  refers  to  his  own  well-known  work  with 
Lamarck's  evening  primrose  as  follows  (pp.  26-29)  : 

"Complying  with  these  conditions,  the  origin  of  species 
may  be  seen  as  easily  as  any  other  phenomenon.  It  is  only 
necessary  to  have  a  plant  in  a  mutable  condi- 
The  work  with  tion.  Not  all  species  are  in  such  a  state  at 
fag  piBiw****  present,  and  therefore  I  have  begun  by  ascer- 
taining which  were  stable  and  which  were  not. 
These  attempts,  of  course,  had  to  be  made  in  the  experi- 
mental garden,  and  large  quantities  of  seed  had  to  be  pro- 
cured and  sown.  Cultivated  plants,  of  course,  had  only  a 
small  chance  to  exhibit  new  qualities,  as  they  have  been  so 
strictly  controlled  during  so  many  years.  Moreover  their 
purity  of  origin  is  in  many  cases  doubtful.  Among  the  wild 
plants  only  those  could  be  expected  to  reward  the  investi- 
gator which  were  of  easy  cultivation.  For  this  reason  I 
have  limited  myself  to  the  trial  of  wild  plants  of  Holland, 
and  have  had  the  good  fortune  to  find  among  them  at  least 
one  species  in  a  state  of  mutability.  It  was  not  really  a 
native  plant,  but  one  probably  introduced  from  America 
or  at  least  belonging  to  an  American  genus.  It  was  the 
great  evening-primrose  or  the  primrose  of  Lamarck.  A 
strain  of  this  beautiful  species  is  growing  on  an  abandoned 
field  in  the  vicinity  of  Hilversum,  at  a  short  distance  from 
Amsterdam.  Here  it  has  escaped  from  a  park,  and  multi- 
plied. In  doing  so  it  has  produced,  and  is  still  producing, 
quite  a  number  of  new  types,  some  of  which  may  be  con- 
sidered as  retrograde  varieties,  while  others  evidently  are 
of  the  nature  of  progressive  elementary  species. 


344  DARWINISM   TO-DAY. 

"This  interesting  plant  has  afforded  me  the  means  of  ob- 
serving directly  how  new  species  originate,  and  of  studying 
the  laws  of  these  changes.  My  researches  have  followed  a 
double  line  of  inquiry.  On  one  side,  I  have  limited  myself 
to  direct  field  observations,  and  to  trials  of  seed,  collected 
from  the  wild  plants  in  their  native  locality.  Obviously  the 
mutations  are  decided  within  the  seed,  and  the  culture  of 
young  plants  from  them  had  no  other  aim  than  that  of 
ascertaining  what  had  occurred  in  the  field.  But  then  the 
many  chances  of  destruction  that  threaten  young  plants  in  a 
wild  state  could  be  avoided  in  the  garden,  where  environ- 
mental factors  can  be  controlled. 

"My  second  line  of  inquiry  was  an  experimental  repetition 
of  the  phenomena  which  were  only  partly  discerned  at  the 
native  locality.  It  was  not  my  aim  to  intrude  into  the 
process,  nor  to  try  to  bring  out  new  features.  My  only  ob- 
ject was  to  submit  to  the  precepts  just  given  concerning 
pure  treatment,  individual  seed-gathering,  exclusion  of 
crosses,  and  accurate  recording  of  all  the  facts.  The  result 
has  been  a  pedigree  which  now  permits  of  stating  the  rela- 
tion between  all  the  descendants  of  my  original  introduced 
plant.  This  pedigree  at  once  exhibits  the  laws  followed  by 
the  mutating  species.  The  main  fact  is,  that  it  does  not 
change  itself  gradually,  but  remains  unaffected  during  all 
succeeding  generations.  It  only  throws  off  new  forms, 
which  are  sharply  contrasted  with  the  parent,  and  which 
are  from  the  very  beginning  as  perfect  and  as  constant,  as 
narrowly  defined,  and  as  pure  of  type  as  might  be  expected 
of  any  species. 

"These  new  species  are  not  produced  once  or  in  single 
individuals,  but  yearly  and  in  large  numbers.  The  whole 
phenomenon  conveys  the  idea  of  a  close  group  of  mutations, 
all  belonging  to  one  single  condition  of  mutability.  Of 
course  this  mutable  state  must  have  had  a  beginning,  as  it 
must  sometime  come  to  an  end.  It  is  to  be  considered  as  a 


OTHER   THEORIES   OF    SPECIES-FORMING.        345 

period  within  the  life-time  of  the  species,  and  probably  it  is 
only  a  small  part  of  it." 

The  following  paragraphs  and  diagram  quoted  from 
Morgan  21  give  an  admirably  concise  statement  of  the  actual 
details  of  the  primrose  mutations  observed  by  de  Vries. 

"We  may  now  proceed  to  examine  the  evidence  from 
which  de  Vries  has  been  led  to  the  general  conclusions  given 
in  the  preceding  pages.     De  Vries   found  at 
Hilversum,  near  Amsterdam,  a  locality  where 


Vries's  experi-  a  number  of  plants  of  the  evening  primrose, 
(Enothera  lamarckiana,  grow  in  large  numbers. 
This  plant  is  an  American  form  [native  to  the  Southern 
United  States]  that  has  been  imported  into  Europe.  It 
often  escapes  from  cultivation,  as  is  the  case  at  Hilversum,. 
where  for  ten  years  it  has  been  growing  wild.  Its  rapid 
increase  in  numbers  in  the  course  of  a  few  years  may  be  one 
of  the  causes  that  have  led  to  the  appearance  of  a  mutation 
period.  The  escaped  plants  showed  fluctuating  variations 
in  nearly  all  of  their  organs.  They  also  had  produced  a 
number  of  abnormal  forms.  Some  of  the  plants  came  to 
maturity  in  one  year,  others  in  two,  or  in  rare  cases  in 
three,  years. 

"A  year  after  the  first  finding  of  these  plants  de  Vries 
observed  two  well-characterised  forms,  which  he  at  once 
recognised  as  new  elementary  species.  One  of  these  was 
O.  brevistylis,  which  occurred  only  as  female  plants.  The 
other  new  species  was  a  smooth-leafed  form  with  a  more 
beautiful  foliage  than  0.  lamarckiana.  This  is  O.  lavifolia* 
It  was  found  that  both  of  these  new  forms  bred  true  from 
self-fertilised  seeds.  At  first  only  a  few  specimens  were 
found,  each  form  in  a  particular  part  of  the  field,  which 
looks  as  though  each  might  have  come  from  the  seeds  of  a 
single  plant. 

"These  two  new  forms,  as  well  as  the  common  O.  la- 
marckiana, were  collected,  and  from  these  plants  there  have 


346 


DARWINISM   TO-DAY. 


arisen  the  three  groups  or  families  of  elementary  species  that 
de  Vries  has  studied.  In  his  garden  other  new  forms  also 
arose  from  those  that  had  been  brought  under  cultivation. 
The  largest  group  and  the  most  important  one  is  that  from 
the  original  O.  lamarckiana  form.  The  accompanying  table 

(ENOTHERA  LAMARCKIANA. 

ELEMENTARY  SPECIES. 


GENERATION. 

-*-"       £         '£ 

1  1  I  ii  h 

O       <3         O       04           J 

Nannella. 

Scintillans. 

VIII  

8  Gener. 
1899 
annual 
7  Gener. 
1898 
annual 
6  Gener. 
1897 
annual 
5  Gener. 
1896 
annual 
4  Gener. 

1895 
annual 
3  Gener. 
1890-91 
biennial 
2  Gener. 
1888-89 
biennial 
i  Gener. 
1886-87 
biennial 

510        1,700 

21 

I 

VII  

9        o      3,000 

II 

5       i 

ii       29        3       i,  800 

9 

V  

25     135       20      8,000 

49     142        6 

IV  

i      15     176        8     14,000 

60      73        i 

nil 

I      IO,COO 

3        3 

ii       

15,000 

5 

5 

i...  

9 

shows  the  mutations  that  arose  between  1887  and  1899  from 
these  plants.  The  seeds  were  selected  in  each  case  from 
self-fertilised  plants  of  the  lamarckiana  form,  so  that  the 
new  plants  appearing  in  each  horizontal  line  are  the 
descendants  in  each  generation  of  lamarckiana  parents.  It 
will  be  observed  that  the  species,  O.  oblongata,  appeared 
again  and  again  in  considerable  numbers,  and  the  same  is 


OTHER   THEORIES   OF   SPECIES-FORMING.        347 

true  for  several  of  the  other  forms  also.  Only  the  two 
species,  O.  gigas  and  O.  scintillans,  appeared  very  rarely. 

"Thus  de  Vries  had,  in  his  seven  generations,  about  fifty 
thousand  plants,  and  about  eight  hundred  of  these  were 
mutations.  When  the  flowers  of  the  new  forms  were  arti- 
ficially fertilised  with  pollen  from  the  flowers  on  the  same 
plant,  or  of  the  same  kind  of  plant,  they  gave  rise  to  forms 
like  themselves,  thus  showing  that  they  are  true  elementary 
species.*  It  is  also  a  point  of  some  interest  to  observe  that 
all  these  forms  differed  from  each  other  in  a  large  number 
of  particulars. 

"Only  one  form,  O.  scintillans,  that  appeared  eight  times, 
is  not  constant  as  are  the  other  species.  When  self- 
fertilised  its  seeds  produce  always  three  other  forms,  O. 
scintillans,  0.  oblongata,  and  O.  lamarckiana.  It  differs  in 
this  respect  from  all  the  other  elementary  species,  which 
mutate  not  more  than  once  in  ten  thousand  individuals. 

"From  the  seeds  of  one  of  the  new  forms,  0.  Icevifolia,  col- 
lected in  the  field,  plants  were  reared,  some  of  which  were 
O.  lamarckiana  and  others  O.  l&vifolia.  They  were  allowed 
to  grow  together,  and  their  descendants  gave  rise  to  the 
same  forms  found  in  the  lamarckiana  family,  described 
above,  namely,  O.  lata,  elliptica,  nannella,  rubrinervis,  and 
also  two  new  species,  O.  spatnlata  and  leptocarpa. 

"In  the  lata  family  only  female  flowers  are  produced,  and, 
therefore,  in  order  to  obtain  seeds  they  were  fertilised  with 
pollen  from  other  species.  Here  also  appeared  some  of  the 
new  species  already  mentioned,  namely,  albida,  nannella, 
lata,  oblongata,  rubrinervis,  and  also  two  new  species,  ellip- 
tica and  subovata. 

"De  Vries  also  watched  the  field  from  which  the  original 
forms  were  obtained,  and  found  there  many  of  the  new 
species  that  appeared  under  cultivation.  These  were  found, 

*  0.  lata  is  always  female,  and  cannot,  therefore,  be  self-fertilised. 
When  crossed  with  O.  lamarckiana  there  is  produced  fifteen  to  twenty 
per  cent,  of  pure  lata  individuals. 


348  DARWINISM   TO-DAY. 

however,  only  as  weak  young  plants  that  rarely  flowered. 
Five  of  the  new  forms  were  seen  either  in  the  Hilversum 
field,  or  else  raised  from  seeds  that  had  been  collected  there. 
These  facts  show -that  the  new  species  are  not  due  to  culti- 
vation, and  that  they  arise  year  after  year  from  the  seeds 
of  the  parent  form,  O.  laniarckiana." 

Since  the  publication  of  de  Vries's  theory  and  the  data 
and  considerations  on  which  it  is  based   (these  considera- 
tions including  an  unusually  keen  and  effective 
Attitude  of  ., .   .  r   ^       ^         .    .         r  r 

naturalists  to-  criticism  of  the  Darwinian  factors  of  species- 
ward  the  muta-  forming)  a  great  deal  of  discussion  of  the 

tious  theory  ( 

theory  has  been  indulged  in.  On  the  whole 
the  theory  has  been  warmly  welcomed  as  the  most  promis- 
ing way  yet  presented  22  out  of  the  difficulties  into  which 
biologists  had  fallen  in  their  attempts  to  explain  satisfactorily 
the  phenomena  of  the  origin  of  species  through  Darwinian 
selection.  And  especially  has  been  welcomed  the  fruitful  idea 
of  unit  species  characters,  and  of  the  indivisibility  and  the 
distinctness  of  such  characters  in  inheritance.  But  with  all 
the  interest  aroused  by  de  Vries's  presentation  of  his  theory, 
and  with  all  the.  eager  scrutiny  of  species  and  records  of 
species-appearing  an  output  of  new  evidence  amazingly 
small  (when  one  stops  to  consider  the  publicity  gained  for 
the  theory  itself  and  its  obvious  need  of  more  confirmatory 
data  of  observation  and  experiment)  has  resulted.  Even 
though  the  answer  may  be  that  experiment  takes  time,  the 
lack  of  new  observational  evidence  of  the  occurrence  of 
mutations,23  and  of  the  origin  of  new  species  through  muta- 
tions in  nature,  is  significant.  It  is  my  belief  that  a  reaction 
against  the  curiously  swift  and  widespread  partial  to  com- 
plete acceptance  of  the  mutation  theory  as  the  sufficient  "way 
out"  of  our  troubles  to  explain  the  origin  of  new  species  will 
soon  occur.  ( See  notes  24,  25,  and  26,  the  appendix  of  this 
chapter,  for  references  to  certain  recent  criticisms  of  the 
mutation  theory.) 


OTHER   THEORIES   OF   SPECIES-FORMING.        349 

In  closing  this  confessedly  inadequate  consideration   of 
the  important  work  and  theorising  of  de  Vries  we  should 
not  fail  to  note  that  the  mutations  theory  is 
in   strong  contrast  to   any   theory   of  species- 


trasted  with  forming  based  on  Lamarckian  principles  in  that 
Lamarckism,  ^  newly  appearing  differences  in  organisms 
leading  to  the  establishment  of  new  species  are  purely  con- 
genital :  that  is,  the  mutations  arise  in  one  or  both  of  the 
sex  cells  and  only  later  appear  in  the  adult  organism.  There 
is  no  question  of  the  transference  to  the  germ-cells  of 
changes  induced  in  the  soma  by  use  or  disuse  or  functional 
stimulus  in  such  a  way  as  to  result  in  the  photographic 
reappearance  of  these  changes  in  the  offspring.  Mutations 
are  true  congenital  or  blastogenic  variations.  "The  muta- 
tion theory,"  well  says  Conklin,27  "is  a  theory  of  the  evolu- 
tion of  organisms  through  the  evolution  of  their  germ-cells." 
The  mutations  theory  is  also  in  sharp  contrast  to  the 
theory  of  species-forming  by  geographical  isolation  (see 
chapter  ix).  According  to  de  Vries  many  dis- 
tinct  species  (de  Vriesian  elementary  species) 


-with  the  isoia-     can  anc[  do  exist  side  by  side  in  the  same  range. 

tion  factor,  .. 

In  fact  they  are  found  to  be  heaped  up  in  the 
centre  of  their  area  of  distribution,  but  are  more  scattered 
at  the  periphery."  28  Now  according  to  Wagner,  Gulick, 
and  Jordan  two  closely  allied  species,  i.  e.,  stock  and  off- 
shoot, are  found  practically  never  to  inhabit  the  same  range, 
except  in  those  cases  where  a  migration  of  one  type  into 
the  territory  of  the  other  has  taken  place  after  the  differ- 
entiation has  been  effected  (by  previous  segregation). 

It  would  carry  us  into  too  extended  a  discussion  to  at- 
tempt to  sum  up  here  the  pertinent  criticism  that  has  been 
directed  against  the  mutations  theory.  As  already  indicated, 
there  is  plenty  of  it  and  of  distinctly  non-negligible  char- 
acter. But  just  now  it  seems  to  me  sufficient  simply  to  call 
attention  to  the  extreme  meagreness  in  quantity  of  the  real 


350  DARWINISM   TO-DAY. 

scientific  evidence  for  the  theory  as  a  theory  capable  of  ex- 
plaining species-forming  as  a  ivhole.  There  is  probably  no 
gainsaying  the  actuality  of  the  occurrence  of  certain  muta- 
tions (in  de  Vries's  sense)  nor  of  their  establishment  of 
certain  apparently  fixed  new  organic  types  (de  Vries's 
elementary  species  of  CEnothera).  But  this  is  very  far 
from  accepting  the  mutations  theory  as  a  sufficient  causal 
explanation  of  the  origin  of  the  hundreds  of  thousands  of 
species  of  animals  and  plants  that  are  now  or  were  formerly 
existent. 

As  for  the  help  that  the  establishment  of  the  mutations 

theory  would  give  those  biologists  who  reject  the  natural 

Morgan's  sum-  section  theory  of  species-forming,   Morgan  26 

mationofthe       writes  as  follows,  summing  up  the  advantages 

advantages  of  .    .        . 

the  mutations      of  the  theory: 

tneoj7-  "i.  Since  the  mutations  appear  fully  formed 

from  the  beginning,  there  is  no  difficulty  in  accounting  for 
the  incipient  stages  in  the  development  of  an  organ,  and 
since  the  organ  may  persist,  even  when  it  has  no  value  to 
the  race,  it  may  become  further  developed  by  later  muta- 
tions and  may  come  to  have  finally  an  important  relation  to 
the  life  of  the  individual. 

"2.  The  new  mutations  may  appear  in  large  numbers,  and 
of  the  different  kinds  those  will  persist  that  can  get  a  foot- 
hold. On  account  of  the  large  number  of  times  that  the 
same  mutations  appear,  the  danger  of  becoming  swamped 
through  crossing  with  the  original  form  will  be  lessened 
in  proportion  to  the  number  of  new  individuals  that  arise. 

"3.  If  the  time  of  reaching  maturity  in  the  new  form  is 
different  from  that  in  the  parent  forms,  then  the  new  species 
will  be  kept  from  crossing  with  the  parent  form,  and  since 
this  new  character  will  be  present  from  the  beginning,  the 
new  form  will  have  much  better  chances  of  surviving  than 
if  a  difference  in  time  of  reaching  maturity  had  to  be  gradu- 
ally acquired. 


OTHER   THEORIES   OF   SPECIES-FORMING.        35L 

"4.  The  new  species  that  appear  may  be  in  some  cases 
already  adapted  to  live  in  a  different  environment  from  that 
occupied  by  the  parent  form;  and  if  so,  it  will  be  isolated 
from  the  beginning,  which  will  be  an  advantage  in  avoiding 
the  bad  effects  of  intercrossing. 

"5.  It  is  well  known  that  the  differences  between  related 
species  consist  largely  in  differences  of  unimportant  organs, 
and  this  is  in  harmony  with  the  mutation  theory,  but  one 
of  the  real  difficulties  of  the  selection  theory. 

"6.  Useless  or  even  slightly  injurious  characters  may 
appear  as  mutations,  and  if  they  do  not  seriously  affect  the 
perpetuation  of  the  race,  they  may  persist." 

Finally,  the  attention  of  students  especially  may  be  called 

to  Bateson's  interesting  suggestion  that  mutations  may  be 

Bateson's  Bug-  simply   pure    Mendelian    recessives    appearing 

gestion  that  mu-  after  a  crossing.     It  would   take   us   too    far 

tations  are  -    ,  ,    A  .    .       .  , 

Mendelian  re-      afield  to  attempt  to   explain   here   to   readers 
cessives.  unacquainted    with    the    Mendelian    principles 

of  inheritance  just  how  Bateson's  suggestion  has  a  certain 
plausibility.  It  must  suffice  to  say  that  Mendel,  and  after 
him  a  considerable  number  of  present-day  students  of 
heredity,  have  shown  that  after  a  crossing  between  two- 
individuals  sharply  contrasting  in  regard  to  some  particular 
character,  as  colour  of  hair,  all  the  offspring  of  the  first 
generation  may  agree  in  showing  but  one  of  the  two  parental 
colours  (the  dominant),  but  that  if  these  first  generation 
'offspring  are  bred  to  each  other,  or  to  similarly  produced  in- 
dividuals, the  members  of  the  second  generation  will  split 
up  as  regards  the  character  in  question,  some  showing  one 
of  the  grand-parental  hair  colours,  and  the  rest  showing  the 
other  one.  Now  breeding  likes  together,  it  would  be  shown 
in  third  generation  groups  that  one  of  these  colours,  and, 
namely,  that  one  called  the  recessive,  which  did  not  appear 
at  all  in  the  first  generation,  will  always  henceforth  breed 
true  while  the  other  colour  may  or  may  not  breed  true  (de- 


352  DARWINISM   TO-DAY. 

pending  on  whether  in  making  the  matings  pure  dominants 
or  cross-bred  dominants  happen  to  be  used).  Thus  the 
sudden  appearance  in  the  second  generation  of  the  latent  or 
recessive  characteristic,  and  its  breeding  true,  are  occur- 
rences which  might  readily  be  interpreted  as  the  appearance 
of  a  mutation  or  true-breeding  sport  by  an  observer  unac- 
quainted with  the  ancestry  of  the  individuals  under  his  eye. 

Alternative  Theories  to  Explain  Secondary  Sexual  Char- 
acters.— Before  closing  this  discussion  of  theories  which 
have  been  proposed  as  substitutes  for  the  Darwinian  selec- 
tion theories  to  explain  the  actual  conditions  in  the  organic 
world  as  we  see  it  to-day,  and  as  we  know  it  to  have  been 
in  past  ages,  we  should  mention,  at  least,  the  few  attempts 
to  formulate  a  substitute  explanation  for  the  existence  of 
secondary  sexual  characters.  The  discrediting  of  the  sexual 
selection  theory  as  such  an  explanation  is  certainly  nearly 
complete.  But  it  is  interesting  to  note  how  lame  and  uncon- 
vincing are  the  proposed  substitute  explanations. 

The  first,  and  most  appealing  one,  is  the  explanation  that 

the  extra  plumes,  wattles,  horns,  the   unusual  display  of 

bright  colours,  etc.,  of  the  males  are  simply  the 

Extra  growths  manifestations    of    an    extra    growth- force    or 

the  result  of  .  i  •«  «.    _t  «        .,1  i      •       ,1       t          1- 

extra  vigour,  vigour  exhibited  by  the  male  in  the  breeding 
season.  The  female  also  may  be  endowed  with 
extra  growth-vigour  at  this  time,  but  it  goes,  in  her  case,  to 
the  formation  of  ova,  to  the  storing  up  of  food  in  or  around 
the  egg  cells.  The  songs,  the  dances,  the  violent  play  and 
antics  of  the  males  common  to  many  species  of  birds,  insects, 
spiders,  etc.,  are  also  attributed  to  this  special  or  sexual 
vigour. 

Now  while  such  secondary  sexual  characters  as  colour, 
plumes,  wattles,  etc.,  might  perhaps  well  enough  seem  to 
be  the  outcome  of  an  extra  growth-vigour,  what  about  such 
special  male  characters  as  the  stridulating  organs  of  male 
katydids  and  crickets,  and  other  similar  complex,  highly 


OTHER   THEORIES   OF   SPECIES-FORMING.        353 

perfected,  adaptive  structures?  A  male  cricket  has  the 
veins  at  the  base  of  one  wing-cover  curiously  and  com- 
plexly modified  in  course  and  in  superficial  structure,  while 
the  veins  of  the  other  wing-cover  are  also  modified  in  a  way 
differing  from  but  exactly  correlated  with  the  venation  of 
the  first  wing,  the  whole  specialisation  resulting  in  a  com- 
bination of  file,  scraper,  and  vibrating  membrane  to  form  the 
effective  musical  instrument  of  the  insect.  Can  such  an 
adaptive  structural  modification  be  conceived  to  be  a  sudden 
bursting  forth  or  result  of  superabundant  growth-force? 
And  many  of  the  secondary  sexual  characters  are  of  this 
class  of  complex  adaptive  specialisations.  The  growth- 
force  explanation  can,  at  best,  explain  but  few  of  the  various 
categories  of  sexual  dimorphism.  Some  explanation  more 
directive  in  its  character  is  needed  for  these  others. 

Even  more  restricted  in  its   application,   and   less  con- 
vincing in  the  assumptions  at  its  very  base,  is  the  curious 
replacement  theory  of  Emery.30     This  investi- 
gator  believes  that  sexual  selection  can  explain 


secondary  sexual  but  few  if  any  cases  of  sexual  dimorphism,  and 

characters. 

would  explain  these  other  cases  largely  by  the 
sudden  appearance  (mutation  or  sport)  of  a  second  form 
of  male  or  female,  the  persistence  for  a  while  of  the  two 
forms  side  by  side,  as  now  exemplified  by  numerous  dimor- 
phic or  polymorphic  (or  di-  or  polychromatic)  species,  and 
then  the  gradual  or  sudden  dying  out  (killing  out  by  selec- 
tion?) of  the  older  original  form  (the  one  resembling  the 
other  sex),  thus  leaving  the  once  dimorphic  sex  represented 
only  by  the  newer  aberrant  form.  While  such  an  explana- 
tion may  possibly  explain  a  few  cases  of  extreme  sexual 
dimorphism  or  dichromatism,  it  certainly  will  not  do  for 
the  many  cases  of  secondary  sexual  difference  constituted 
by  the  existence  in  one  sex  of  some  one  or  few  particular 
adaptive  specialisations  for  music-making,  scent-producing, 
or  weapon-forming,  not  possessed  by  the  other  sex. 


354  DARWINISM   TO-DAY. 

Cunningham81  (and  also  at  about  the  same  time  Wigles- 

worth)  in  1898  suggested,  on  a  neo-Lamarckian  basis,  that 

secondary  sexual  characters  were  due  to  the 

Cunninffliain's         .....  .  « 

explanation  of      stimulation  of  parts  through  use  or  external 

secondary  sexual  violence  or  irritation.  Cunningham  would  ex- 
characters,  ,  .  ,  . 

plain  all  adaptations  as  derived  from  variations 

actually  induced  by  responses  or  reactions  to  the  environ- 
ment. His  theory  of  the  origin  of  secondary  sexual  char- 
acters would  simply  be  the  explanation  of  the  adaptive  dif- 
ferences between  two  individuals  of  a  species  on  the  same 
basis  as  the  explanation  of  the  adaptive  differences  between 
individuals  of  different  species.  His  argument  is  summed 
up  as  follows :  "Selection  assumes  the  occurrence  of  varia- 
tions ;  the  variations  must  either  be  similarly  indefinite  and 
promiscuous  in  all  cases,  or  they  must  be  different  in  differ- 
ent cases — that  is,  in  different  species,  different  sexes,  dif- 
ferent stages  of  life.  If  they  are  different  in  different  cases, 
then  selection  is  a  very  unimportant  matter,  for  the  chief 
questions  are  evidently  what  are  the  differences  and  what 
made  them  differ.  To  deny  that  the  variations  have  always 
been  different  in  different  cases  is  to  deny  the  most  evident 
facts ;  such  denial  might  be  possible  when  we  consider  only 
the  difference  between  species,  but  it  is  impossible  when 
we  study  the  differences  between  the  sexes  in  the  same 
species  and  between  different  stages  in  the  same  individual. 
In  all  cases  the  variations  correspond  to  differences  in  habits 
and  mode  of  life,  and  in  many  cases  are  of  the  same  kind 
as  the  changes  known  to  be  produced  in  the  individual  by 
special  stimulation  or  special  activity  of  organs ;  this  is  true 
of  many  and  probably  of  all  cases  of  adaptation.  The  gen- 
eral conclusion  is  that  adaptation  is  not  produced  indirectly 
by  the  selection  from  indefinite  variations,  but  directly  by  the 
influence  of  stimulation  in  modifying  the  growth  of  the 
parts  or  organs  of  the  body." 

Wallace"  has  suggested  that  the  differences  in  color- 


OTHER   THEORIES   OF   SPECIES-FORMING.        355 

ation  between  males  and  females  are  due  largely  to  the 
necessity  of  the  better  protection  of  the  young 

Wallace's         producing:  and  (in  the  case  of  birds  and  mam- 
suggestion,  .  . 

mals)  young  protecting  and  caring  for  female, 

and  hence  the  acquirement  on  her  part  of  a  dull  incon- 
spicuous protective  colour-pattern.  Wallace's  large  ac- 
quaintanceship with  birds  and  butterflies  enables  him  to 
illustrate  his  theory  by  many  apparently  confirmatory  ex- 
amples, but  as  soon  as  one  stops  to  consider  the  matter 
thoughtfully  the  impossibility  of  the  general  or  even  wide 
application  of  this  explanation  of  secondary  sexual  char- 
acters is  at  once  apparent^  It  is  necessarily  limited  to  one 
single  category  of  sexual  differences. 

Barrett-Hamilton  sa  has  noted  that  both  sexes  of  the  sal- 
mon (Onchorhynchus)  become  markedly  discoloured  during 
the  spawning  season.  The  discoloration  is  accompanied  by 
overgrowth  or  hypertrophy,  especially  of  the  jaws.  "I  can- 
not believe,"  he  says,  "that  this  is  of  an  aesthetic  nature,  since 
these  phenomena  terminate  in  the  death  of  the  fish.  They 
seem  to  be,  in  fact,  merely  the  outward  symptoms  of  what, 
as  I  have  persuaded  myself  from  personal  observation  in 
Kamschatka,  is  a  pathological  condition  accompanying,  and 
perhaps  resulting  from,  the  growth  of  the  ova  and  milt. 
I  regard  the  whole  metamorphosis  as  a  purely  excretory 
phenomenon  resulting  from  the  upsetting  of  the  metab- 
olism due  to  the  concentration  of  the  whole  vital  force 
on  the  effort  to  produce  the  greatest  possible  amount  of 
spawn. 

"May  not  such  a  state  of  things  be  invoked  to  explain  the 
nuptial  changes  of  our  own  salmon  so  strangely  assumed 
before  and  lost  after  the  breeding-season  ?  Is  it  not  possible 
that  in  the  phenomena  displayed  by  the  spawning  Oncho- 
rhynchus we  may  have  a  clue  to  the  origin  of  the  hitherto 
inexplicable  temporary  and  permanent  sexual  characters 
of  the  vertebrates  and  even  of  some  invertebrates,  of  which 


356  DARWINISM   TO-DAY. 

it  may  be  that  the  origin  has  been  primarily  excretory  and 
only  secondarily  protective  or  aesthetic  ?" 

The  plain  truth  is  that  the  satisfactory,  all-explaining  ex- 
planation of  secondary  sexual  characters  and  sexual  dimor- 
phism as  a  whole  is  yet  to  be  formulated. 

APPENDIX. 

1  At  some  time  between  1855  and   1865,  Gregor  Johann  Mendel, 
an  Augustinian  monk  in  the  small  Austrian  village  of  Briinn,  car- 
Mendel  and        ried    on    pedigree    cultures    of   peas   and    some    other 
his  work,  plants  in  the  gardens  of  his  cloister.     From  this  work 

he  derived  data  that  he  read,  together  with  his  interpretation  of 
their  significance,  before  meetings  of  the  Natural  History  Society 
of  Briinn,  and  which,  in  the  same  year  of  their  reading,  1865,  were 
published  under  the  title  "Experiments  in  Plant-hybridisation,"  in 
the  Abhandlnngen  (Vol.  IV.)  of  the  society.  Mendel  was  the  son 
of  a  peasant  and  had  been  educated  in  Augustinian  foundations  and 
ordained  priest.  For  two  or  three  years  he  studied  physics  and 
natural  science  in  Vienna,  and  refers  to  himself  as  a  student  of 
Kollar.  He  became  Abbot  of  his  cloister,  and  was  for  a  time 
president  of  the  Briinn  Natural  History  Society.  Such  are  the 
essential  details  of  the  education  and  situation  of  the  man  whose 
name  will  undoubtedly  live  forever  in  the  annals  of  biological 
science.  For  the  observations,  experiments,  and  conclusions  of 
Mendel  on  inheritance  have  taken  their  place  already  as  matters  of 
fundamental  importance  in  the  study  of  heredity.  It  would  take 
us  too  far  afield  even  to  outline  Mendel's  work  and  derived  "princi- 
ples of  heredity,"  but  the  interested  reader  can  find  an  admirable 
exposition  and  discussion  of  them  (together  with  translations  of 
Mendel's  own  papers)  in  Bateson's  "Mendel's  Principles  of  Hered- 
ity," 1902. 

For  an  excellent  exposition  of  Mendel's  work  and  other  similar 
work  by  botanists,  see  Lotsy,  J.  P.,  "Vorlesungen  iiber  Descendenz- 
theorien,"  Vol.  I,  chap,  viii,  1906. 

Cuenot,  in  L'Annee  Biologique,  Vol.  VII,  for  1902,  pp.  58-77, 
gives  an  excellent  review  of  the  work  of  Mendel,  de  Vries,  Cor- 
rens,  and  Tschermak ;  and  a  bibliography,  relating  to  the  so-called 
Mendelian  laws  of  the  principles  of  heredity. 

Bateson,  in  "Progressus  rei  Botannicae,"  Vol.  I,  pp.  368-468,  1907, 
gives  a  complete  abstract  of  the  nature  of  the  work  and  its  results 
which  has  been  done  on  the  Mendelian  problem  from  the  time  of 


OTHER   THEORIES   OF   SPECIES-FORMING.        357 

Mendel  to  the  present.  The  bibliography  in  connection  with  this 
paper  is  practically  complete  up  to  the  date  of  its  making." 

2  Correns,  C.  G.,  "Uber  Levkoyen-Bastarde,  zur  Kenntniss  der 
Grenzen  der  Mendel'schen  Regeln,"  Botan.  Centralbl.,  LXXXIV, 

References  to  P-  97>  19°°;  "Uber  Bastarde  zwischen  Rassen  von 
recent  work  on  Zea  Mays,"  Ber.  Deut.  Bot.  Ges.,  XIX,  211  (1901); 
Mendelism,  "Bastarde  zwischen  Maisrassen,  Bibliotheca  Bota- 

nica,"  Heft  53,  1901 ;  "Uber  Bastardirungs-Versuche  mit  Mirabilis- 
Sippen,"  Ber.  Deut.  Bot.  Ges.,  XX,  594-608,  1903. 

8  T.  E.  Tschermak,  "Uber  kiinstliche  Kreuzung  bei  Pisum  sati- 
vum,"  Zeitschr.  f.  d.  Landwirthsch.  Versuchswesen,  III,  465-555, 
1900;  "Weitere  Beitrage  iiber  Verschiedenswerthigkeit  der 
Merkmale  bei  Kreuzung  von  Erbsen  und  Bohnen,"  ibid.  IV,  641  ff., 
1901 ;  "Uber  Ziichtung  neuer  Getreiderassen  mittelst  kiinstlicher 
Kreuzung,"  ibid.  IV,  1902.  "Die  Theorie  der  Kryptomerie  und  des 
Kryptohybridismus,"  Beihefte  2.  Bot.  Centralbl,  XVI,  25  pp.,  1903; 
"Weitere  Kreuzungsstudien  an  Erbsen,"  Zeitschrift  f.  d.  Landwirth- 
Versuchswesen  in  Oesterr.,  106  pp.,  1904. 

4  See  Darwin,  "Animals  and  Plants  Under  Domestication,"  Vol. 
I,  chap,  iii,  p.  104.  "In  some  few  instances  new  breeds  [of  sheep] 

Darwin  on  nave  suddenly  originated ;  thus  in  1791  a  ram-lamb  was 
race  origin  from  born  in  Massachusetts,  having  short  crooked  legs  and 
sports,  a  iong  back,  like  a  turnspit  dog.  From  this  one  lamb 

the  otter,  or  ancon,  a  semi-monstrous  breed,  was  raised;  as  these 
sheep  could  not  leap  over  the  fences  it  was  thought  that  they  would 
be  valuable;  but  they  have  been  supplanted  by  merinos,  and  thus 
exterminated.  The  sheep  are  remarkable  from  transmitting  their 
character  so  truly  that  Colonel  Humphreys  never  heard  of  'but  one 
questionable  case'  of  an  ancon  ram  and  ewe  not  producing  ancon 
offspring.  When  they  are  crossed  with  other  breeds  the  offspring, 
with  rare  exceptions,  instead  of  being  intermediate  in  character, 
perfectly  resemble  either  parent ;  even  one  of  twins  has  resembled 
one  parent  and  the  second  the  other.  Lastly,  'the  ancons  have  been 
observed  to  keep  together,  separating  themselves  from  the  rest  of 
the  flock  when  put  into  enclosures  with  other  sheep.' 

"A  more  interesting  case  has  been  recorded  in  the  Report  of 
the  Juries  for  the  Great  Exhibition  (1851),  namely,  the  produc- 
tion of  a  merino  ram-lamb  on  the  Mauchamp  farm,  in  1828,  which 
was  remarkable  for  its  long,  smooth,  straight,  and  silky  wool.  By 
the  year  1833  M.  Graux  had  raised  rams  enough  to  serve  his  whole 
flock,  and  after  a  few  more  years  he  was  able  to  sell  stock  of  his 
new  breed.  So  peculiar  and  valuable  is  the  wool,  that  it  sells  at 
25  per  cent,  above  the  best  merino  wool :  even  the  fleeces  of  half- 
bred  animals  are  valuable,  and  are  known  in  France  as  the 


358  DARWINISM   TO-DAY. 

'Mauchamp-merino.'  It  is  interesting,  as  showing  how  generally 
any  marked  deviation  of  structure  is  accompanied  by  other  devia- 
tions, that  the  first  ram  and  his  immediate  offspring  were  of  small 
size,  with  large  heads,  long  necks,  narrow  chests,  and  long  flanks, 
but  these  blemishes  were  removed  by  judicious  crosses  and  selec- 
tion. The  long  smooth  wool  was  also  correlated  with  smooth  horns ; 
and  as  horns  and  hair  are  homologous  structures,  we  can  under- 
stand the  meaning  of  this  correlation.  If  the  Mauchamp  and  ancon 
breeds  had  originated  a  century  or  two  ago,  we  should  have  no 
record  of  their  birth ;  and  many  a  naturalist  would  no  doubt  have 
insisted,  especially  in  the  case  of  the  Mauchamp  race,  that  they  had 
each  descended  from,  or  been  crossed  with,  some  unknown  aborig- 
inal form." 

The  Paraguay  cattle  are  a  hornless  race  which  is  composed  of 
the  descendants  of  a  hornless  bull  which  was  born  in  Paraguay  in 
1770. 

A  recent  interesting  case  wholly  parallel  with  those  just  recorded, 
is  that  of  the  Polled  Herefords  originating  in  1889  in  Kansas,  U. 
S.  A,. (see  Guthrie,  W.  W.,  "History  of  Polled  Herefords,"  in  Proc. 
Am.  Breeders'  Assoc.,  Vol.  II,  pp.  93-95*  1906). 

"In  the  fall  of  1889,  W.  W.  Guthrie, -Sr.,  of  Atchison,  Kansas, 
now  deceased,  discovered  among  the  calves  that  had  been  weaned 
A  recent  ex-  at  ^s  ranc^  in  Chase  County,  Kansas,  one  with  Here- 
ample  of  race  ford  markings  which  was  perfectly  polled.  In  his 
origin  from  a  herd  were  purebred  Shorthorn  as  well  as  purebred 
sport  in  cattle,  Hereford  cows.  Two  purebred  Hereford  bulls  were 
at  the  head  of  the  herd.  This  calf  was  the  product  of  a  three- 
quarter  Hereford  and  one-quarter  Shorthorn  cow  by  one  of  the 
two  purebred  Hereford  bulls,  Grateful  3d,  No.  8,001,  and  Treasurer, 
No.  10,585.  Discovery,  as  the  calf  was  subsequently  named,  was  a 
well-formed  animal,  with  a  good  loin,  and  well-developed  hind- 
quarters, and  had  the  Hereford  colour  and  markings,  with  body 
more  on  the  type  of  the  Shorthorn.  At  three  years  of  age  he 
weighed,  without  special  feeding,  1,986  Ibs. 

"It  then  occurred  to  Mr.  Guthrie  that  by  using  this  animal  he 
might  in  time  establish  a  herd  of  polled  Herefords,  and  that  the 
experiment  was  at  least  worth  trying.  Shortly  afterwards,  he 
happened  to  meet  on  the  train  Chancellor  Snow,  of  the  Kansas 
State  University,  on  his  way  to  lecture  before  the  Atchison  High 
School  on  evolution,  and  during  their  several  hours  conversation 
discussed  with  him  the  proposition  of  animal  architecture.  The 
Chancellor  agreed  that  the  proposition  of  establishing  a  polled 
Hereford  herd  was  one  worth  considering,  and  Mr.  Guthrie  deter- 
mined to  carry  out  his  ideas  along  this  line. 


OTHER   THEORIES   OF   SPECIES-FORMING.        359 

"When  Discovery  matured  it  was  found  that  his  calves  from 
horned  cows  were  all  hornless.  In  1893,  a  two-year-old  bull  and 
six  heifers  were  selected  and  brought  to  Atchison  County,  where 
the  experiment  was  carried  on  under  the  personal  supervision  of 
Mr.  Guthrie  and  with  very  encouraging  results. 

"On  October  31,  1898,  Mr.  Guthrie  purchased  at  the  Kansas  City 
Scott  &  Whitmann  sale  four  purebred  Hereford  heifers.  The  calves 
from  these  horned  heifers  by  a  descendant  of  Discovery  were  found 
to  be  in  every  instance  polled,  only  two  showing  scurs,  scarcely 
noticeable,  and  loose  in  the  skin.  A  number  of  purebred  Hereford 
heifers  were  later  obtained  from  the  Funkhouser  herd,  and  still 
later  others  from  the  Armour  herd,  and  equally  good  results  were 
obtained. 

"Eight  head  of  polled  Herefords  were  exhibited  by  Mr.  Guthrie 
at  the  Omaha  Exposition,  and,  while  these  animals  did  not  present 
the  finished  appearance  of  modern  show  cattle,  not  having  been 
forced  from  date  of  birth,  they  attracted  such  attention  that  articles 
on  the  herd  were  published  in  the  newspapers  and  periodicals 
throughout  this  country,  and  even  in  such  far-away  lands  as  Aus- 
tralia and  New  Zealand. 

"The  desirability  of  Herefords  without  horns,  the  one  objection 
which  Hereford  breeders  had  been  willing  to  admit,  becoming  appa- 
rent, other  Hereford  breeders  began  to  take  notice  of  an  occasional 
polled  calf,  freaks  of  nature  as  they  were  considered,  appearing 
in  their  herds,  and  soon  a  brisk  demand  for  polled  bulls  developed, 
animals  being  shipped  as  far  north  as  South  Dakota,  and  Wiscon- 
sin, and  as  far  south  as  Texas.  Breeders  in  many  instances  have 
reported  that  in  their  horned  herds,  after  several  years'  breeding, 
not  a  single  calf  had  come  with  horns,  and  only  occasionally  would 
slight  scurs,  loose  in  the  skin,  appear."  .  .  . 

"In  December,  1904,  four  head  of  polled  Herefords  from  West 
Virginia  were  exhibited  at  the  International  Live  Stock  Show  at 
Chicago  in  connection  with  horned  Herefords,  and  during  the  past 
season  a  larger  number  from  the  same  State  were  exhibited  through- 
out the  eastern  circuit  of  fairs.  At  the  American  Royal  Cattle 
Show  at  Kansas  City,  last  October,  seven  head  from  the  original 
herd  were  exhibited.  As  a  result  of  these  exhibits,  many  horned 
Hereford  breeders  are  now  turning  their  attention  to  the  subject  of 
breeding  Herefords  without  horns,  and  so  great  has  become  the 
demand  for  animals  with  which  to  start  polled  herds  that  at  the 
last  meet  of  the  National  Polled  Hereford  Breeders'  Association  it 
was  found  that  the  members  were  unable  to  supply  enough  young 
bulls  to  meet  the  demand. 

"Quite  a  number  of  purebred  Hereford  calves,   termed   'freaks' 


36° 


DARWINISM   TO-DAY. 


or  'sports/  have  been  dropped  in  this  country,  and  some  have  been 
kept.  The  President  of  the  National  Polled  Hereford  Breeders' 
Association  has  a  perfectly  polled  cow,  the  produce  of  one  of  his 
purebred  horned  Hereford  cows  by  a  purebred  horned  Hereford 
bull,  and  has  lately  purchased  a  purebred  polled  Hereford  bull. 
The  original  herd  now  contains  two  polled  males  and  a  number  of 
polled  females,  descended  direct  from  purebred  Herefords.  The 
above  animals  are  registered  in  the  American  Hereford  Record. 

"During  a  trip  through  England  several  years  ago,  Mr.  Guthrie 
made  inquiry  among  Hereford  breeders  and  found  that,  while  an 
occasional  polled  animal  had  been  calved,  they  were  considered  as 
freaks  of  nature  by  the  owners  and  butchered." 

6  Bateson,  Wm.,  "Materials  for  the  Study  of  Variation,"  1894. 

8  Kolliker,  A.  von,  "Uber  die  Darwin'sche  Schopfungstheorie," 
Zeitsch.  f.  wiss.  Zool,  Vol.  XIV,  pp.  174-186,  1864. 

7  Dall,  W.  H.,  1877. 

8  Galton,  Francis,  "Natural  Inheritance,"  p.  32,  1889. 

9  Galton,  Francis,  loc.  cit.  p.  27,  "The  distinction  between  primary 
Galton's  dis-      an(^   subordinate   positions   of   stability   will   be   made 

cussionofspe-  clearer  by  the  help  of  Fig.  I,  which  is  drawn  from  a 
cific  stability.  model  I  made.  The  model  has  more  sides,  but  Fig. 
i  suffices  for  illustration.  It  is  a  polygonal  slab  that  can  be  made  to 
stand  on  any  one  of  its  edges  when  set  upon  a  level  table,  and  is 


intended  to  illustrate  the  meaning  of  primary  and  subordinate 
stability  in  organic  structures,  although  the  conditions  of  these  must 
be  far  more  complex  than  anything  we  have  wits  to  imagine.  The 
model  and  the  organic  structure  have  the  cardinal  fact  in  com- 
mon, that  if  either  is  disturbed  without  transgressing  the  range 
of  its  stability,  it  will  tend  to  reestablish  itself,  but  if  the  range  is 
overpassed  it  will  topple  over  into  a  new  position;  also  that  both 
of  them  are  more  likely  to  topple  over  towards  the  position  of 
primary  stability,  than  away  from  it. 

"The   ultimate   point  to   be   illustrated   is  this.     Though   a    long 
established  race  habitually  breeds  true  to  its  kind,  subject  to  small 


OTHER   THEORIES   OF   SPECIES-FORMING.        361 

unstable  deviations,  yet  every  now  and  then  the  offspring  of  these 
deviations  do  not  tend  to  revert,  but  possess  some  small  stability 
of  their  own.  They,  therefore,  have  the  character  of  sub-types, 
always,  however,  with  a  reserved  tendency,  under  strained  condi- 
tions, to  revert  to  the  earlier  type.  The  model  further  illustrates 
the  fact  that  sometimes  a  sport  may  occur  of  such  marked  pecu- 
liarity and  stability  as  to  rank  as  a  new  type,  capable  of  becoming 
the  origin  of  a  new  race  with  very  little  assistance  on  the  part  of 
natural  selection.  Also,  that  a  new  type  may  be  reached  without 
any  large  single  stride,  but  through  a  fortunate  and  rapid  succession 
of  many  small  ones. 

"The  model  is  a  polygonal  slab,  the  polygon  being  one  that 
might  have  been  described  within  an  oval,  and  it  is  so  shaped  as 
to  stand  on  any  one  of  its  edges.  When  the  slab  rests,  as  in  Fig  i, 
on  the  edge  A  B,  corresponding  to  the  shorter  diameter  of  the  oval,, 
it  stands  in  its  most  stable  position,  and  in  one  from  which  it  is 
equally  difficult  to  dislodge  it  by  a  tilt  either  forwards  or  back- 
wards. So  long  as  it  is  merely  tilted  it  will  fall  back  on  being 
left  alone,  and  its  position  when  merely  tilted  corresponds  to  a  simple 
deviation.  But  when  it  is  pushed  with  sufficient  force,  it  will  tumble 
on  to  the  next  edge,  B  C,  into  a  new  position  of  stability.  It  will 
rest  there,  but  less  securely  than  in  its  first  position;  moreover,  its 
range  of  stability  will  no  longer  be  disposed  symmetrically.  A  com- 
paratively slight  push  from  the  front  will  suffice  to  make  it  tumble 
back,  a  comparatively  heavy  push  from  behind  is  needed  to  make  it 
tumble  forward.  If  it  be  tumbled  over  into  a  third  position  (not 
shown  in  the  figure),  the  process  just  described  may  recur  with 
exaggerated  effect,  and  similarly  for  many  subsequent  ones.  If,, 
however,  the  slab  is  at  length  brought  to  rest  on  the  edge  C  D,  most 
nearly  corresponding  to  its  longest  diameter,  the  next  onward  push, 
which  may  be  very  slight,  will  suffice  to  topple  it  over  into  an 
entirely  new  system  of  stability;  in  other  words,  a  'sport'  comes 
suddenly  into  existence.  Or  the  figure  might  have  been  drawn  with 
its  longest  diameter  passing  into  a  projecting  spur,  so  that  a  push 
of  extreme  strength  would  be  required  to  topple  it  entirely  over. 

"If  the  first  position,  A  B,  is  taken  to  represent  a  type,  the  other 
portions  will  represent  sub-types.  All  the  stable  positions  on  the 
same  side  of  the  longer  diameter  are  subordinate  to  the  first  position. 
On  whichever  of  them  the  polygon  may  stand,  its  principal  tendency 
on  being  seriously  disturbed  will  be  to  fall  back  towards  the  first 
position;  yet  each  position  is  stable  within  certain  limits. 

"Consequently,  the  model  illustrates  how  the  following  condi- 
tions may  co-exist:  (i)  variability  within  narrow  limits  without 
prejudice  to  the  purity  of  the  breed;  (2)  partly  stable  sub-types;; 


362  DARWINISM   TO-DAY. 

(3)  tendency,  when  much  disturbed,  to  revert  from  a  sub-type  to 
an  earlier  form;  (4)  occasional  sports  which  may  give  rise  to  new 
types." 

10  Emery,  C,  "Gedanken  zur  Descendenz-  und  Vererbungstheorie," 
Biolog.  Centralbl,  Vol.  XIII,  pp.  397-420,  1893. 

11  Korschinsky,     S.,     "Heterogenesis     und    Evolution,"     Naturw. 
Wochenscrift,  Vol.  XIV,  pp.  273-278,  1899;  also  "Heterogenesis  u. 
Evolution,"  Flora,  oder  Allg.  Bot.  Zeit.,  Erganzungsbd.  89,  pp.  240- 
368,  1901. 

12  De  Vries,  H.,   ''Die  Mutationstheorie,"   Vol.  I,   1901,   Vol.  II, 
1903. 

Beferences  to  13  De    Vries>    H->    "Species    and    Varieties,    Their 

discussions  by  Origin  by  Mutation"   (ed.  by  MacDougal),  1905. 

de  Vries  of  spe-  14De    Vries,    H.,    "Die    Mutationstheorie,"    Vol.    I, 

sies-forming,  p    ^   IQOI 

15  De  Vries,  H.,  "Die  Mutationstheorie,  Vol.  I,  p.  362,  1901. 
10  De  Vries,  H.,  "Species  and  Varieties,"  p.  6. 

17  De  Vries,  H.,  "Species  and  Varieties,"  pp.  8-9. 

18  De  Vries,  H.,  "Species  and  Varieties,"  p.  10. 

19  De  Vries,  H.,  "Species  and  Varieties,"  p.  13. 

20  For  an  excellent  exposition  and  discussion  of  the  de  Vries  muta- 
tion theory  and  mutations,  see  Lotsy,  J.  P.,  "Vorlesungen  iiber  De- 
scendenztheorien,"  Vol.  I,  chaps,  xiv  and  xv,  1906. 

21  Morgan,  T.  H.,  "Evolution  and  Adaptation,"  pp.  294-295,  1903. 

22  As  evidence  of  the  interest  and  favour  with  which  American 
biologists  have  received  the  theory,  the  six  addresses  on  "the  muta- 

American  ^on  tneory  °f  organic  evolution"  delivered  before  the 
opinion  of  the  American  Society  of  Naturalists  at  Philadelphia, 
mutations  December  28,  1904,  may  be  especially  referred  to. 

theory,  These  addresses  by  naturalists  distinguished  for  their 

work  in  different  phases  of  biology,  as  systematic  and  oecologic 
botany,  cytology,  human  anatomy,  animal  cecology,  etc.,  are  printed 
in  Science,  N.  S.,  Vol.  XXI,  pp.  521-543  (April  7,  1905),  and  from 
them  I  quote  various  paragraphs  indicating  some  of  the  points 
of  view  of  the  speakers  and  some  of  the  arguments  advanced  in 
favour  of  the  theory. 

"On  the  whole,  it  appears  that  the  formation  of  new  breeds  be- 
gins with  the  discovery  of  an  exceptional  individual,  or  with  the 
production  of  such  an  individual  by  means  of  cross-breeding.  Such 
exceptional  individuals  are  mutations"  (Castle,  p.  524). 

"Modification  of  character  by  selection,  when  sharply  alternative 
conditions  (t.  e.,  mutations)  are  not  present  in  the  stock,  is  an 
exceeding  difficult  and  slow  process,  and  its  results  of  questionable 
permanency.  Even  in  so-called  'improved'  breeds,  which  are  sup- 


OTHER   THEORIES   OF   SPECIES-FORMING.        363 

posed  to  have  been  produced  by  this  process,  it  is  more  probable 
that  the  result  obtained  represents  the  summation  of  a  series  of 
mutations  rather  than  of  a  series  of  ordinary  fluctuating  variations. 
For  mutations  are  permanent:  variations  transitory"  (Castle,  p. 

524). 

"It  is  to  my  mind  impossible  to  find  any  support  for  a  theory  of 
evolution  by  minute  changes  from  the  study  of  anatomical  varia- 
tions. I  should  not  venture  to  say,  on  the  other  hand,  that  they 
give  any  direct  support  to  the  theory  of  mutation :  but,  at  least,  they 
are  not  in  disaccord  with  it"  (Dwight,  p.  532). 

"It  seemed  necessary  to  discuss  ethological  characters  at  some 
length  for  the  purpose  of  vindicating  their  importance.  Having 
attempted  this,  I  may  say  that  these  characters  seem  to  me  to  offer 
even  fewer  difficulties  than  the  morphological  characters  to  the 
acceptance  of  the  mutation  theory,  for  the  reason  that  the  ethological 
and  psychological  processes  are  conceived  primarily  as  qualities 
and  not  quantities.  Thus  the  psychical  elements,  i.  e.,  the  simple 
feelings,  cravings,  and  sensations,  are  disparate  qualitative  processes 
which  cannot  be  derived  from  one  another  or  from  some  more 
undifferentiated  process.  This  is  still  more  evident  in  the  case  of  the 
complex  psychical  phenomena.  Similarly,  instincts,  with  which 
ethology  is  most  concerned,  when  resolved  into  their  simplest  com- 
ponents are  seen  to  consist  of  discrete  reactions  which  cannot  be 
shown  to  arise  from  one  another.  Although,  on  the  other  hand, 
the  measurable  intensities  and  durations  of  the  reactions  are  anal- 
ogous to  the  fluctuating  structural  variations,  it  is  even  more  difficult 
for  the  psychologist  to  conceive  of  a  particular  feeling,  craving, 
or  sensation  as  arising  from  the  greater  or  less  intensity  or  dura- 
tion of  some  other  psychic  process,  than  it  is  for  the  morphologist 
to  conceive  of  the  origin  of  new  characters  from  the  fluctuating 
variations  of  structure"  (Wheeler,  p.  539). 

"Mutation  is  even  more  urgently  demanded  for  the  explanation 
of  many  other  instincts,  especially  those  of  symbiotic  and  parasitic 
species  and  of  species  with  profound  and  sudden  metamorphosis. 
In  these  cases,  a  particular  activity,  on  which  most  often  depends 
the  life  of  the  individual  or  of  its  progeny,  has  to  be  performed 
with  a  high  degree  of  proficiency  at  its  very  phylogenetic  incep- 
tion or  it  can  be  of  no  advantage  to  the  individual  or  the  race. 
Such  cases,  with  which  you  are  all  familiar,  have  ever  been  the 
insurmountable  obstacle  to  the  evolution  of  instincts  on  the  theory 
of  fluctuating  variations  and  natural  selection.  The  theory  of 
organic  selection  seems  to  me  merely  to  conceal  but  not  to  over- 
come the  difficulties.  The  mutation  theory  frankly  avoids  the  diffi- 
culties even  if  it  fails  to  throw  any  light  on  the  origin  of  the  muta- 


364  DARWINISM   TO-DAY. 

tions  and  bundles  this  into  the  germ-plasma.  It  is,  of  course,  no 
objection  to  the  theory  that  it  leaves  something  under  the  heavens  to 
be  accounted  for.  This  is  rather  to  be  regarded  as  one  of  its  chief 
virtues.  As  working  naturalists  we  have  reason  to  be  most  sus- 
picious of  the  theories  that  explain  everything"  (Wheeler,  pp.  539- 
540). 

"In  view  of  the  amount  of  orderly  and  well-authenticated  evi- 
dence now  at  hand,  it  may  be  regarded  as  demonstrated  that  char- 
acters, of  appreciable  physiological  value,  originate,  appear  in  new 
combinations  or  become  latent,  in  hereditary  series  of  organisms, 
in  such  a  manner  as  to  constitute  distinct  breaks  in  descent"  (Mac- 
Dougal,  p.  540). 

23  Some  of  de  Vries's  experiments  and  observations  on  the  La- 
marck primrose  have  been  repeated  (with  naturally  some  variation) 
in  the  New  York  Botanic  Garden,  by  MacDougal  and  assistants. 
See  MacDougal,  D.  T.,  "Mutation  in  Plants,"  Amer.  Nat.,  VoL 
XXXVII,  pp.  737-770,  1003;  also,  "Mutants  and  Hybrids  of  the 
CEnotheras,"  by  D.  T.  MacDougal,  assisted  by  A.  M.  Vail, 
G.  H.  Shull,  and  J.  K.  Small,  Pub.  No.  24,  Carnegie  Inst.  of  Wash., 
1005. 

I  am  aware  of  the  rather  sweeping  statements  made  by  some 
biologists  touching  the  probability  of  the  origin  by  mutation  of  many 
species,  or  at  least,  races  of  animals  and  plants.  For  example, 
Castle  (Science,  N.  S.,  Vol.  XXI,  p.  522,  1905)  says:  "So  far, 
however,  as  these  various  sorts  of  evidence  go,  they  indicate  that 
the  material  used  by  breeders  for  the  formation  of  new  breeds  con- 
sists almost  exclusively  of  mutations."  And  Davenport  (Science, 
N.  S.,  Vol.  XXII,  p.  372,  1905)  says:  "Undoubtedly  many,  if  not 
most,  of  the  characteristics  of  the  races  of  domesticated  animals  and 
probably  feral  species  have  arisen  by  mutation."  He  then  refers, 
as  example,  to  the  qualities  that  differentiate  the  races  of  poultry — 
feathered  feet,  rose  comb,  elongated  tail,  taillessness,  silky 
feathers,  frizzled  feathers,  cerebral  hernia,  polydactyl  feet,  albinism, 
and  many  others.  But  I  have  been  assured  by  Luther  Burbank, 
the  most  experienced  and  distinguished  plant  breeder  in  this  country, 
that  the  many  races  of  plants  actually  produced  by  him  have  not 
been  derived  from  mutations.  But  on  the  contrary,  that  the  selec- 
tion of  small  variations — a  special  abundance  and  variety  of  these 
variations  usually  being  induced  by  hybridisation  and  by  change  of 
environment — has  been  his  almost  exclusively  relied-on  means  for 
producing  new  forms  of  plants.  As  a  matter  of  fact  the  cases 
actually  adduced  by  upholders  of  the  de  Vriesian  theory  as  supports 
for  it  are  astonishingly  few.  Castle  (Science,  N.  S.,  Vol.  XXI,  pp. 
522-523,  1905)  calls  attention  to  the  sudden  appearance  of  a  super- 


OTHER   THEORIES   OF   SPECIES-FORMING.        365 

numerary  fourth  digit  on  one  of  the  hind  feet  of  one  of  nine  young 
produced  by  a  certain  pair  of  guinea-pigs.     "Neither  of  the  parents 
had  such  a  digit,  nor  had  I  ever  heard  of  the  existence  of  such  a 
character  before,  either  in  any  of  the  wild  Caviedae  or  among  domes- 
ticated cavies  or  guinea-pigs.      Further,   I   have  been  able  to  find 
no  reference  to  such  a  thing  in  the  literature  of  the  group,  though 
I  have  several  times  since  found  this  same  mutation  in  other  herds 
of  guinea-pigs.     The  mother  of  my  four-toed  pig  never  produced 
another   similar   individual,   though   she   was   the   mother   in   all   of 
thirty  young.     The  father,  however,   who  sired  in  all   139  young, 
had  five  other  young  with  extra  toes,  but  these  were  all  by  females 
descended  from  himself,  so  that  it  seems  certain  that  the  mutation 
had  its  origin  in  this  particular  male.    By  breeding  together  the  four- 
toed  young  and  selecting  only  the  best  of  their  offspring,  I  was  able 
within  three  generations  to  establish  a  race  with  a  well-developed 
fourth  toe  on  either  hind  foot.    This  race  was  not  created  by  selec- 
tion,  though   it   was   improved  by  that   means."     Castle   also   had 
another  mutation   appear  in  a  second  family  of  guinea-pigs.     "A 
few  individuals  were  found  to  have  hair  about  twice  as  long  as 
that  of  their  parents  and  grandparents.     Intermediate  conditions  did 
not    occur.      Long-haired    individuals    mated    together    were    found 
to  produce  only  long-haired  young,  so  that  a  new  breed  was  already 
fully    established   without    the    exercise    of    any    selection."      Casey 
(Science,  N.   S.,  Vol.  XXII,  p.   308,    1905)    presents  a  number   of 
facts  touching  the  sudden  appearance  of  certain  molluscous  genera 
in  early  Eocene  strata,  and  in  certain  Lower  Oligocene  rocks,  which 
seem    to    be    evidence    for    the    mutations    theory.      "At    least,    the 
mutation  theory  is  evidently  the  best  that   has  been   advanced  to 
account  for  these  known  facts."    Scott  (Science,  N.  S.,  Vol.  XXII. 
pp.  271-282)  attempts  to  make  out  a  case  for  the  mutational  origin 
of  nine  kinds  of  North  American  birds  that,  because  of  their  rarity 
and  the  obscure  character  of  the  records  of  their  occurrence,  are 
mostly  rather  puzzling  to   ornithologists.      (They  are  all   included 
in   the   "hypothetical  list"   of  the   American   Ornithologists'   Union 
Check-List.)     But  this  attempt  is  robbed  of  much  significance  by 
Allen's  critical  discussion  of  it  (Science,  N.  S.,  Vol.  XXII,  pp.  431- 
434,   1905).     Morgan    (Harper's  Monthly  Mag.,  Vol.  CVI,  p.  478) 
refers  to  the  "japanned"  turkeys,  a  kind  of  bronze-shouldered  aber- 
ration that  appears  occasionally  in  flocks  of  turkeys,  as  "mutations." 
These   turkeys   are   called  attention   to   by    Darwin    ("Variation   of 
Animals  and  Plants  Under  Domestication,"  Vol.  I,  p.  305).     Indeed, 
more   cases   of   such   mutations   are   referred   to   and   described   by 
Darwin  himself  than  by  all  those  who  have  attempted  recently  to 
adduce  examples,  for  the  support  of  the  mutations  theory,  of  an 


366  DARWINISM   TO-DAY. 

alleged  case  of  sudden  appearances  of  modified  animals  or  plants 
that  seem  to  breed  true.  But  these  infrequent  prepotent  sports, 
or  discontinuous  variations,  do  little  to  furnish  any  convincing 
foundation  for  de  Vries's  theory.  Far  better  than  all  of  them  are 
de  Vries's  own  long  and  carefully  observed  primrose  mutations. 
Here,  besides  a  few  single  mutations,,  were  several  that  appeared 
in  considerable  numbers,  which  is  a  condition  almost  imperatively 
necessary  for  the  successful  propagation  of  a  new  organic  type. 

A  recent  record  of  an  alleged  case  of  mutation  is  Schaffner's, 
"A  Successful  Mutant  of  Verbena  without  External  Isolation,"  in 
Ohio  Naturalist,  Vol.  VII,  pp.  31-34,  December,  1906. 

As  Davenport  ("The  Mutation  Theory  in  Animal  Evolution," 
Science,  N.  S.,  Vol.  XXIV,  pp.  556-558,  November,  1906)  puts  it :  'The 
real  argument  for  discontinuity  in  evolution  is  the  occurrence  of 
characteristics  in  nature  that  are  discontinuous  and  which  never 
show  intergrades.  The  mere  fact  of  discontinuity  between  species 
of  the  same  genus  is  not  sufficient  to  prove  that  they  have  arisen 
by  mutation.  It  must  be  shown  that  the  differential  characters  are 
in  essence  discontinuous.  The  practical  way  to  get  at  the  true 
nature  of  characteristics,  whether  continuous  or  discontinuous,  is 
by  their  behaviour  in  inheritance.  If,  in  cross-breeding,  a  char- 
acter tends  to  blend  with  the  dissimilar  character  of  its  consort  it 
must  be  concluded  that  the  character  can  be  fractionised  and  inter- 
grades  are  possible.  If,  on  the  contrary,  the  characteristic  refuses 
to  blend,  but  comes  out  of  the  cross  intact,  as  it  went  in,  the  con- 
clusion seems  justified  that  the  characteristic  is  essentially  integral 
and  must  have  arisen  completely  formed,  and  hence  discon- 
tinuously. 

"Using  this  criterion,  I  have  of  late  been  testing  the  application 
of  the  mutation  theory  to  animals  and  have  had  an  opportunity  to 
examine  the  experiments  of  others.  Some  of  the  work  has  been 
done  on  the  characteristics  of  domesticated  'races/  others  on  wild 
varieties.  There  seems  to  be  no  difference  in  the  behaviour  of 
characteristics  of  domesticated  and  wild  varieties.  The  result  is 
that  most  characteristics,  but  not  all,  fail  to  blend  and  are  strictly 
alternative  in  inheritance.  I  interpret  this  to  mean  that  the  char- 
acteristic depends  on  a  certain  molecular  condition  that  does  not 
fractionise.  The  inference  is  that  if  the  characteristic  is  incapable  of 
gradations  now  it  has  always  been  so  and  hence  must  have  arisen 
without  gradations,  i.  e.,  discontinuously.  Examples  of  such  discon- 
tinuous characteristics  are  the  spots  in  the  elytra  of  certain  beetles, 
the  crest  on  the  canary,  the  form  of  the  comb  in  poultry,  extra  toes, 
black  plumage,  and  colour  of  iris.  One  who  sees  the  striking 
failure  of  these  characteristics  and  many  others  to  be  modified  in 


OTHER   THEORIES   OF   SPECIES-FORMING.       367 

any  important  way  will  feel  convinced  that  they  are  not  capable 
of  forming  intergrades  and  hence  could  not  have  arisen  gradu- 
ally." 

24  C.  B.  Davenport  ("Evolution  Without  Mutation,"  Jour,  of 
Exper.  Zool,  Vol.  II,  pp.  I37-M3,  1905),  in  a  recent  short  paper, 
adduces  facts  concerning  the  variation  and  evolution 
examplesflrfspe-  of  Pectens,  which  lead  him  to  conclude  that  the  races 
oies-origin  by  of  Pecten  inhabiting  different  geographical  regions 
slight  continu-  are  connected  so  plainly  by  integrating  variations 
ous  change,  ^at  there  can  be  no  question  of  mutations  in  con- 
nection with  their  origin.  They  must  have  arisen  through  evolu- 
tion by  trivial  variation.  Davenport  concludes  his  paper  with  the 
following  summary:  "The  process  of  evolution  has  taken  place  by 
various  methods  and  not  always  in  the  same  way.  It  is  not  more 
justifiable  to  maintain  that  all  evolution  is  by  mutation  than  that 
evolution  has  always  proceeded  by  slow  stages.  The  best  evidence 
for  slow  evolution  is  found  in  wide-ranging  species  which,  while 
differing  greatly  at  the  limits  of  their  range,  exhibit  all  gradations  in 
intermediate  localities  (Melospiza,  Pecten}  ;  also  in  fossil  series 
(Pecten  eboreus  and  P.  irradians}  where  the  change  from  one  hori- 
zon to  the  next  is  of  a  quantitative  order.  Thus  evolution  may  take 
place  without  mutation." 

Naturalists  whose  special  field  of  study  is  systematic  and  fau- 
nistic  rather  than  morphologic  or  experimental,  seem  to  be  slow  to 
Memam's  nn<^  much  good  in  the  mutations  theory.  Indeed, 
criticism  of  the  some  of  them  seem  to  be  quick  to  find  much  that  is 
mutations  theory,  \\\  m  j^  For  example,  Merriam  and  Allen,  deans  of 
American  faunistic  students  of  birds  and  mammals,  are  both  strong 
antagonists  of  the  mutations  theory.  Merriam,  in  an  address  as 
chairman  of  the  zoological  section  at  the  1905  meeting  of  the  Ameri- 
can Association  for  the  Advancement  of  Science  ("Is  Mutation  the 
Factor  in  the  Evolution  of  the  Higher  Vertebrates  ?"  Science,  N.  S., 
Vol.  XXIII,  pp.  241-257,  1906),  shows  by  the  use  of  illustrations- 
drawn  from  the  distribution  and  taxonomy  of  American  chipmunks 
and  ground  squirrels  that  the  mutations  theory  cannot  by  any 
means  explain  all  species-forming.  "My  argument,"  says  Merriam, 
"is  not  that  species  of  plants  may  not  in  rare  cases  arise  in  perpetu- 
ation of  sport  characters,  as  de  Vries  believes  they  do,  but  admitting 
this,  my  contention  is  that  the  overwhelming  majority  of  plants,, 
and  so  far  as  known,  all  animals,  originate  in  the  generally  recog- 
nised way  by  the  gradual  development  of  minute  variations.  The 
theory  of  origin  of  species  by  mutation,  therefore,  far  from  being 
a  great  principle  in  biology,  as  some  seem  to  believe,  appears  to  be 
one  of  a  hundred  minor  factors  to  be  considered  in  rare  cases  as  a. 


368  DARWINISM   TO-DAY. 

possible  explanation  of  the  origin  of  particular  species  of  plants, 
but  so  far  as  known,  not  applicable  in  the  case  of  animals." 

Certain  naturalists  even  go  so  far  as  to  express  some  doubt  about 
the  value  of  the  mutations  observed  by  de  Vries  in  the  primroses. 
This  doubt  touches  two  points.  First,  the  possibility  that  the 
mutating  primroses  are  not  pure  cultures,  but  are  hybrids;  second, 
that  when  an  investigation  of  the  wild  primroses  in  their  native 
locality  (southern  United  States)  is  made  it  may  be  found 
that  these  primroses  in  true  wild  condition  do  not  mutate.  Touch- 
ing these  two  points,  it  should  be  said  that  de  Vries  has  convinced 
himself  that  his  cultures  are  pure,  and  has  tried  to  discover  the 
actual  conditions  existent  among  the  primroses  in  their  native 
habitat.  As  a  matter  of  fact,  the  Lamarckian  primrose  seems  to  be 
practically  extinct  as  a  wild  species.  De  Vries  ("Uber  die  Dauer 
der  Mutationsperiode  bei  (Enothera  Lamarckiana"  Ber.  Deutsch.  Bot. 
Gesell.,  Vol.  XXIII,  pp.  382-387,  1905)  found  specimens  of  (Enothera 
Lamarckiana  in  three  botanical  collections  in  the  United  States. 
These  specimens  were  collected  in  Florida  and  Kentucky.  How- 
ever, since  these  specimens  were  taken  (the  Florida  ones  in  1860) 
the  species  has  not  been  observed,  perhaps  on  account  of  lack  of 
close  observation,  perhaps  because  actually  disappeared.  There- 
fore the  question  whether  the  Lamarckian  primrose  mutates  in 
wild  condition  remains  undecided. 

25  The  most  considerable  critical  discussion  and  analysis  of  the 
mutations  theory  is  that  made  by  Plate  in  his  review  of  Morgan's 
Plate's  criti-  "Evolution  and  Adaptation.  (Plate,  L.,  "Darwinismus 
cism  of  the  nm-  kontra  Mutationstheorie,"  Archiv  f.  Rassen-  und  Ci- 
tations theory,  sellschafts-Biologie,  Vol.  Ill,  pp.  183-200,  1906.)  In 
the  course  of  his  critical  review  of  Morgan's  book  (which  book 
is  at  once  an  attack  on  Darwinism  and  an  upholding  of  the  muta- 
tions theory),  Plate  points  out  keenly  and  strongly  the  weak  places 
in  de  Vries's  theory.  As  a  general  substitute  for  the  natural  selec- 
tion theory  as  an  explanation  of  adaptation  as  well  as  species-form- 
ing, the  mutations  theory  is  open  to  many  of  the  same  objections  as 
the  Darwinian  theories.  Plate  takes  up,  serially,  Morgan's  claims 
for  the  mutation  theory  and  readily  shows  their  unconvincing  char- 
acter. I  quote  some  of  this  analysis,  as  follows: 

"Es  ist  von  Interesse  zu  sehen,  welche  Griinde  Morgan  bestim- 
men,  der  Mutationstheorie  trotz  ihrer  fundamentalen  Mangel  den 
Vorzug  zu  geben  vor  der  alten  Darwin'schen  Auffassung.  Auf.  S. 
298  zahlt  er  die  'Vorziige'  dieser  Theorie  auf,  die  aber  meines 
Erachtens  alle  vor  der  Kritik  nicht  standhalten. 

"  'i.  Da  die  Mutationen  von  Anfang  an  vollstandig  ausgebildet 
auftreten,  fallt  die  Schwierigkeit  fort,  die  Anfangsstadien  in  der 


OTHER   THEORIES   OF   SPECIES-FORMING.        369 

Entwicklung  eines  Organs  zu  erklaren,  und  da  das  Organ  sich 
^rhalten  kann,  selbst  wenn  es  keinen  Wert  fur  die  Rasse  hat,  kann 
es  durch  spatere  Mutationen  weiter  entwickelt  warden  und  schliess- 
lich  eine  wichtige  Beziehung  zum  Leben  des  Individuums  erlangen.' 

"Die  erwahnte  Schwierigkeit,  die  Anfangsstadien  niitzlicher  Struk- 
turen  und  Organe  nach  der  Darwin'schen  Auffassung  zu  erklaren, 
lasst  sich  nicht  leugnen,  aber  sie  ist,  wie  ich  in  dem  oben  erwahnten  * 
Buche  gezeigt  zu  haben  glaube  (S.  34-51),  zu  iiberwinden,  besonders 
dann,  wenn  man  in  der  Vererbungsfrage  Gegner  von  Weismann  ist 
und  annimmt,  dass  ein  durch  Generationen  ausgeiibter  Reiz  sich  in 
seinem  Effekt  allmahlich  steigert  (Prinzip  der  Orthogenese)  und 
wenn  man  sich  dariiber  klar  ist — was  Morgan  vollstandig  entgangen 
zu  sein  scheint — das  der  Konkurrenzkampf  zwischen  zwei  Arten 
sehr  oft  nicht  sofort,  sondern  im  Laufe  von  Generationen  bloss 
durch  die  grossere  Fruchtbarkeit  entschieden  wird,  diese  aber  kor- 
relativ  durch  geringfugige  morphologische  Unterschiede  und  unbe- 
deutende  Anderungen  in  der  Lebensweise  wesentlich  beeinflusst 
werden  kann.  Durch  die  Mutationstheorie  wird  aber  jene  Schwie- 
rigkeit in  keiner  Weise  gehoben,  denn  erstens  stellen  die  Mutationen, 
wie  auch  Morgan  zugibt,  meistens  geringfugige  Abanderungen  dar, 
welche  die  morphologische  Breite  der  Fluktuationen  nicht  iiber- 
treffen.  Man  kann  also  nicht  annehmen,  dass  das  Stadium  der 
Nutzlichkeit  mit  einem  Sprunge  erreicht  wird,  dass  etwa  der 
Rollriissel  des  Schmetterlings  plotzlich  aus  kauenden  Kiefern 
hervorging.  Es  mussten  also  eine  Anzahl  Mutationen  in  ganz 
bestimmter  Weise  aufeinander  folgen,  was,  wie  eben  schon  ange- 
deutet  wurde,  nach  unsern  jetzigen  Kenntnissen  von  diesen  regel- 
und  richtungslosen  Variationen  unmoglich  ist. 

"  '2.  Die  neuen  Mutationen  konnen  in  zahlreichen  Exemplaren 
auftreten  und  von  ihren  verschiedenen  Sorten  werden  diejenigen  sich 
erhalten,  welche  festen  Fuss  fassen  konnen.  Da  dieselben  Muta- 
tionen zu  wiederholten  malen  auftreten  konnen,  wird  die  Gefahr, 
durch  Kreuzung  mit  der  Stammform  vernichtet  zu  werden,  im  Ver- 
haltnis  zu  der  Zahl  der  neu  auftretenden  Individuen  geringer.'  Dass 
•eine  neue  Mutation  bei  ihrem  ersten  Auftreten  sofort  in  zahlreichen 
Exemplaren  erscheint,  ist  ein  ausserst  seltenes  Vorkommnis.  Mir 
ist  aus  der  Literatur  nur  der  eine  Fall  der  Whiteschen  Washington- 
Tomate  bekannt,  welche  sofort  zu  100%  aus  der  Varietat  Acme 
zwei  Jahre  hintereinander  auf  derselben  Lokalitat  entstanden  sein 
soil.  Die  Mutationen  der  Gartenpflanzen  sind  alle  von  einer  oder 
einigen  wenigen  Stammexemplaren  ausgegangen,  waren  also  extreme 

*Plate,  L.,  "Uber  die  Bedeutung  der  Darwin'schen  Selections- 
prinzip,"  1903. 


370  DARWINISM   TO-DAY. 

Singularvariationen,  und  erst  durch  Isolation  und  Selbstbefruchtung 
hat  man  grossere  Mengen  von  Individuen  erzielt.  Die  zoologischen 
Mutationen  weisen,  soweit  ihr  Ursprung  bekannt  ist,  immer  auf 
ein  Stammtier :  so  das  1791  in  Massachusetts  entstandene  Otter schaf, 
die  1770  von  einem  hornlosen  Stier  ausgegangene  Rinderasse  in 
Paraguay  und  die  Rasse  der  Mauchampschafe,  welche  1828  zuerst  in 
einem  Lamm,  das  von  Merino-Eltecn~-alNjjj£nrnte,  auftrat.  Schwanz- 
lose  Katzen,  Ziegen  mit  4  Hornern,  Menschen  mit  6  Fingern  sind 
weitere  Belege  dafiir,  dass'  solche  sprungartige  Abanderungen 
grosste  Seltenheiten  sind.  Da  Selbstbefruchtung  im  Tierreich  im 
allgemeinen  als  ausgeschlossen  gelten  kann,  so  konnen  solche  Falle 
nur  durch  grosste  Inzucht  und  strengste  Selektion  zum  Range  einer 
Rasse  erhoben  werden.  Correns,*  der  selbst  grosse  Verdienste  um 
die  Erkenntnis  der  Mutationen  sich  erworben  hat,  schreibt  (S.  34) 
iiber  die  Notwendigkeit  der  Selbstbefruchtung:  'Es  geniigt  aber 
nicht,  die  Samen  einer  neu  entstandenen  Form  zu  sammeln  und 
auszusaen ;  es  muss  auch  dafiir  Sorge  getragen  werden,  dass  diese 
Samen  ausschliesslich  durch  Selbstbefruchtnng  entstehen  oder 
wenigstens,  wenn  mehrere  abgeanderte  Individuen  verwendbar 
sind,  durch  Inzucht.  Bei  der  Bestaubung  der  abgeanderten 
neuen  Pflanzen  mit  dem  Pollen  einer  zur  alten  unverandert 
gebliebenen  Form  gehorenden  Pflanze,  die  der  Wind  oder  die 
Insekten  ausftihren  konnen,  entsteht  ein  Bastard  zwischen  der 
neuen  und  der  alten  Form,  indem  die  letztere  fast  immer  die 
erstere  zunachst  so  vollkommen  unterdriickt,  dass  der  Bastard 
genau  wie  die  alte  Form  aussieht.  Die  neue  Form  kann  dann 
zwar  in  der  folgenden  Generation  des  Bastards  wieder  zum  Vor- 
schein  kommen ;  in  der  Praxis  beurteilt  man  aber  die  Erblichkeit  nach 
der  ersten  Generation.'  Wenn  also  in  der  freien  Natur  eine  einzelne 
Mutation  auftritt,  so  wird  sie  als  Regel  mit  der  Stammform  sich 
kreuzen  und  Bastarde  erzeugen,  die  entweder  nach  dem  Mendelschen 
Gesetz  wie  die  Stammform  aussehen  oder  den  neuen  Charakter  in 
abgeschwachtem  Grade  besitzen.  Die  meisten  von  diesen  Bastarden 
werden  sich  wieder  mit  der  unveranderten  Stammform  kreuzen,  da 
deren  Individuen  weitaus  in  der  Majoritat  sind,  und  so  muss  der 
neue  Charakter  in  einigen  Generationen  wieder  ausgeloscht  werden, 
selbst  wenn  er  in  der  ersten  Zeit  in  einzelnen  Individuen  ab  und  zu 
zum  Vorschein  kommt.t  Es  gilt  also  meines  Erachtens  fur  die 
Mutationen  dieselbe  Regel  wie  fur  die  Fluktuationen :  Singular- 

*  Correns,  C,  "Experimentelle  Untersuchungen  iiber  die  Entste- 
hung  der  Arten  auf  botan.  Gebiet."  Diese  Zeitschr.,  I,  1904,  S. 
27-52.  Wie  man  sieht,  vertritt  Correns  hier  die  Dominanz  der 
phyletisch  alteren  Form. 

fVgl.  hierzu  S.  185,  Anm. 


OTHER   THEORIES   OF   SPECIES-FORMING.       371 

variationen  spielen  bei  der  Evolution  keine  Rolle.  sondern  nur 
Pluralvariationen,  wenn  wir  absehen  von  jenen  vereinzelten  Fallen, 
in  denen  ein  giinstiger  Zufall  fur  die  Isolation  der  Singularvariation 
sorgt.  Wahrend  aber  bei  den  Fluktuationen  sich  leicht  eine  neue 
Rasse  bilden  kann,  da  immer  viele  Individuen  nach  dieser  oder  jener 
Richtung  vom  Durchschnitt  abweichen  oder  durch  die  ausseren 
Faktoren  in  gleicher  Weise  verandert  werden,  liegen  die  Verhaltnisse 
fur  die  Mutationen  sehr  viel  ungiinstiger. 

"  '3-  Wenn  die  Zeit  der  Geschlechtsreife  bei  der  neuen  Form, 
abweicht  von  der  der  Elternform,  vermag  sich  die  neue  ATI  nicht 
mit  der  Elternform  zu  kreuzen,  und  da  dieser  neue  Charakter  von 
Anfang  an  vorhanden  ist,  wird  die  neue  Form  bessere  Aussichten 
haben  am  Leben  zu  bleiben  als  wenn  der  Zeitunterschied  der  Ge- 
schlechtsreife erst  allmahlich  erworben  werden  miisste.'  Morgan 
erwahnt  hier  eine  ganz  spezielle  Form  der  sexuellen  Isolation.  Man 
braucht  jedoch  nicht  anzunehmen,  dass  dieselbe  von  den  Fluktua- 
tionen allmahlich  erworben  wird ;  sie  ist  entweder  von  vornherein 
da,  d.  h.  die  neue  Varietat  wird  in  der  Mehrzahl  ihrer  Individuen 
fruher  oder  spater  geschlechtsreif  als  die  Stammform,  oder  diese 
Schranke  tritt  iiberhaupt  nicht  auf.  In  diesem  Punkte  verhalten 
sich  also  die  Fluktuationen  genau  so  wie  die  Mutationen. 

"  '4.  Die  neuen  Arten,  welche  erscheinen,  konnen  in  einigen 
Fallen  schon  an  eine  andere  Umgebung  angepasst  sein  als  die  von 
der  Stammform  bewohnte ;  in  diesem  Falle  werden  sie  von  Anfang 
an  isolirt  sein,  was  einen  Vorzug  bei  der  Vermeidung  der  schlechten 
Einflusse  der  Kreuzung  bedeutet.'  Auch  diese  biologische  Isolation 
gilt  natiirlich  in  demselben  Masse  fur  die  Fluktuationen.  ja  sie  muss 
bei  ihnen  eine  weit  grossere  Rolle  spielen,  denn  nach  der  Darwin- 
'schen  Auffassung  wandern  gewisse  Individuen  allmahlich  in  ein 
neues  Wohngebiet  ein  und  passen  sich  auf  Grund  ihrer  Variabilitat 
an  dieses  im  Laufe  von  Generationen  an.  Wenn  aber  unter  den 
Exemplaren  einer  in  der  Ebene  lebenden  Art  plotzlich  einige  muta- 
tive  Individuen  auftreten,  welche  fur  das  Leben  im  Gebirge  einge- 
richtet  sind,  so  ist  gar  nicht  zu  verstehen,  wie  solche,  Mutationen 
sofort  die  ihnen  zusagende  Wohnstatte  resp.  Lebensweise  auffinden. 

"  '5.  Es  ist  wohl  bekannt,  dass  die  Unterschiede  verwandter 
Arten  zum  grossen  Teile  Differenzen  unwichtiger  Organe  sind,  und 
dies  steht  in  Harmonic  mit  der  Mutationstheorie,  bildet  aber  eine 
der  wirklichen  Schwierigkeiten  der  Selektionstheorie. 

"  '6.  Nutzlose  oder  selbst  leicht  schadliche  Charaktere  konnen  als 
Mutationen  auftreten  und  sich  erhalten,  wenn  sie  die  Fortdauer  der 
Rasse  nicht  ernstlich  beeinflussen.' 

"Morgan  muss  sich  wirklich  sehr  wenig  in  die  Darwinischen 
Gedanken  eingearbeitet  haben,  wenn  er  nicht  einsieht,  dass  die 


372  DARWINISM    TO-DAY. 

Selektionstheorie  iiber  den  Ursprung  der  Variationen  iiberhaupt 
nichts  aussagt,  sondern  diese  einfach  als  gegeben  hinnimmt,  mogen 
sie  nur  durch  aussere  Faktoren  oder  unbekannte  innere  Ursachen 
hervorgerufen  werden  und  mogen  sie  niitzlich,  schadlich  oder 
indifferent  ausfallen.  In  dieser  Hinsicht  steht  sie  auf  demselben 
Boden  wie  die  Mutationstheorie,  welche  gleichfalls  den  Ursprung 
der  Mutationen  nicht  aufklart,  sondern  diese  als  plotzlich  vorhanden 
ansieht.  Die  Selektionstheorie  sucht  uns  nur  klar^zu  machen,  wie 
durch  den  Kampf  urns  Dasein  die  komplizirten  niitzlichen  Ein- 
richtungen,  die  Anpassungen,  allmahlich  entstehen  konnten,  und  da 
nahverwandte  Arten  haufig  in  dem  Grade  der  Ausbildung  solcher 
Anpassungen — man  denke  z.  B.  an  die  Unterschiede  zwischen  dem 
indischen  und  afrikanischen  Elefanten  im  Bau  der  Russelspitze 
und  der  Ohren — voneinander  abweichen,  macht  sie  bis  zu  einem  ge- 
wissen  Grade  auch  den  'origin  of  species'  verstandlich.*  Morgan 
wirft  in  seinem  Buche  immer  und  immer  wieder  ganz  unberechtigter 
Weise  dem  Darwinismus  vor,  er  behaupte  'That  adaptations  have 
arisen  because  of  their  usefulness.'  Selbst  die  extremsten  Anhanger 
Darwins  haben  immer  nur  gesagt :  gewisse  Variationen  bleiben 
erhalten,  weil  sie  niitzlich  sind,  und  indem  eine  niitzliche  Stufe  zu 
der  andern  allmahlich  addirt  wird,  entstehen  schliesslich  jene 
auffallenden  Einrichtungen,  die  wir  'Anpassungen'  nennen.  Genau 
denselben  Standpunkt  nimmt  die  Mutationstheorie  ein.  Auch  fur 
sie  ist  der  Kampf  urns  Dasein — dieses  Wort  wie  bei  Darwin  im 
weitesten  Sinne  genommen — das  oberste  regulatorische  Prinzip  der 
organischen  Natur,  welches  die  dauerfahigen  Mutationen  von  den 
schadlichen  sondert,  dadurch  die  Evolutionen  in  ganz  bestimmte 
Bahnen  drangt  und  langsam  die  Entstehung  der  Anpassungen  er- 
moglicht.  Dadurch  dass  der  Kampf  urns  Dasein  das  'Uberleben  des 
Passendsten'  bedingt,  schafft  er  etwas  Positives  und  macht  uns 
die  mit  dem  Wechsel  der  Lebensweise  und  Umgebung  stets  wech- 
selnden  Formen  der  Anpassungen  verstandlich." 

28  Klebs,  the  eminent  plant  physiologist,  keenly  criticises  the  muta- 
tions theory  in  his  paper  on  "Willkiirliche  Entwicklungsanderungen 
bei  Pflanzen,"  1903.  See  also  Copeland,  E.  B.,  "The  Variation  of 
Some  California  Plants,"  Botan.  Gas.,  Vol.  XXXVIII,  pp.  401-426, 
1904.  In  this  paper  the  author  describes  some  striking  aberrant  forms 
of  oak  and  fern  leaves,  but  shows  that  between  these  mutation-like 
forms  and  the  modal  forms  intergrading  steps  exist.  Copeland 

*  Es  ist  also  nicht  richtig,  wenn  Morgan  (S.  454)  von  der  Dar- 
win'schen  Theorie  behauptet,  sie  werfe  die  Frage  des  Ursprungs 
der  Arten  zusammen  mit  der  des  Ursprungs  der  Anpassungen. 
Beide  Probleme  konnen  zusammenfallen,  aber  sie  brauchen  es 
nicht. 


OTHER   THEORIES   OF   SPECIES-FORMING.       373 

discusses  keenly  the  mutations  of  de  Vries  and  finds  in  them  noth- 
ing radically  different  either  in  character  or  behaviour  from  the 
Darwinian  fluctuating  variations. 

27  Conklin,  E.  C,  Science,  N.  S.,  Vol.  XXI,  p.  525,  1905. 

28  Morgan,  "Evolution  and  Adaptation,"  p.  292,  1903. 

29  Morgan,  "Evolution  and  Adaptation,"  pp.  298-299,  1903. 
References  to         30  Emery,     C,     "Gedanken  zur    Descendenz-     und 

theories  explain-  Vererbungstheorie,"   Biolog.    Centralblatt,   Vol.    XIV, 

ing  secondary        pp.  397-420,   1893. 

sexual  characters,      si  Cunningham,  J.   T.,  "The   Species,  the   Sex,  and 

the   Individual/  Natural  Science,  Vol.   XIII,  pp.    184-192,  233-239, 

1898. 

32  Wallace,  A.  R.,  "Tropical  Nature,"  1878. 

33  Barrett-Hamilton,  G.  E.  H.,  "Note  on  a  Possible  Mode  of  Origin 
of  some  Nuptial  and  Sexual  Characters  in  Vertebrates,"  Anatom. 
Anzeig.,  Vol.  XVIII,  pp.  47-48,  1900. 


CHAPTER  XII. 
DARWINISM'S  PRESENT  STANDING. 

A  RIVER  rises  from  a  perennial  spring  on  the  mountain  side ; 

gravitation  compels  the  water .  to  keep  moving,   and   rock 

Natural  selec-   walls,   intervening  hills,  and   soft  loam   banks 

tion  the  final       determine  the  course  of  the  stream.    The  living 

&rbit6r  in 

descent,  stream  of  descent  finds  its  never-failing  primal 

source  in  ever-appearing  variations ;  the  eternal  flux  of 
Nature,  coupled  with  this  inevitable  primal  variation,  com- 
pels the  stream  to  keep  always  in  motion,  and  selection 
guides  it  along  the  ways  of  least  resistance.  Although  there 
can  be  no  modification,  no  evolution,  without  variation,  yet 
neither  can  this  variation,  whatever  its  character  and  extent, 
whether  slight  and  fluctuating,  large  and  mutational,  de- 
terminate or  fortuitous,  long  compel  descent  to  go  contrary 
to'  adaptation.  And  the  guardian  of  the  course  is  natural 
selection.  Selection  will  inexorably  bar  the  forward  move- 
ment, will  certainly  extinguish  the  direction  of  any  ortho- 
genetic  process,  Nagelian,  Eimerian,  or  de  Vriesian,  which  is 
not  fit,  that  is,  not  adaptive.  Darwinism,  then,  as  the  natural 
selection  of  the  fit,  the  final  arbiter  in  descent  control, 
stands  unscathed,  clear  and  high  above  the  obscuring  cloud 
of  battle.  At  least,  so  it  seems  to  me.  But  Darwinism,  as 
the  all-sufficient  or  even  most  important  causo-mechanical 
factor  in  species-forming  and  hence  as  the  sufficient  ex- 
planation of  descent,  is  discredited  and  cast  down.1  At 
least,  again,  so  it  seems  to  me.  But  Darwin  himself  claimed 
no  Allmacht  for  selection.  Darwin  may  well  cry  to  be  saved 
from  his  friends ! 

374 


DARWINISM'S   PRESENT   STANDING.  375 

The  selection  theories  do  not  satisfy  present-day  biolo- 
gists 2    as    efficient    causal    explanations    of    species-trans- 
Natural  formation.     The  fluctuating  variations  are  not 

selection  not  a  sufficient  handles  for  natural  selection ;  the 
nationofspSes"  hosts  of  trivial,  indifferent  species  differences 
forming.  are  no^  the  result  of  an  adaptively  selecting 

agent.  On  the  other  hand  the  declarations  of  Korschinsky, 
Wolff,  Driesch,  and  others  that  natural  selection  is  non- 
existent, is  a  vagary,  a  form  of  speech,  or  a  negligible  influ- 
ence in  descent,  are  unconvincing ;  they  are  unproved. 

And  these  bitter  antagonists  of  selection  are  especially  un- 
convincing when  they  come  to  offer  a  replacing  theory,  an 

alternative  explanation  of  transformation  and 
The  weakness 

of  the  replacing  descent.  To  my  mind  every  theory  of  hetero- 
genesis,  of  orthogenesis,  or  of  modification  by 
the  transmission  of  acquired  characters,  confesses  itself  ulti- 
mately subordinate  to  the  natural  selection  theory.  How- 
ever independent  of  selection  and  Darwinism  may  be  the 
beginnings  of  modification,  the  incipiency  of  new  species 
and  of  new  lines  of  descent;  even,  indeed,  however  neces- 
sary to  natural  selection  some  auxiliary  or  supporting 
theory  to  account  for  the  beginnings  of  change  confessedly 
is,  the  working  factor  or  influence  postulated  by  any  such 
auxiliary  theory  soon  finds  its .  independence  lost,  its  influ- 
ence in  evolution  dominated  and  controlled  by  natural  selec- 
tion. As  soon  as  the  new  modifications,  the  new  species 
characters,  the  new  lines  of  descent,  if  they  may  come  so 
far,  attain  that  degree  of  development  where  they  have  to 
submit  to  the  test  of  utility,  of  fitness,  just  there  they  are 
practically  delivered  over  to  the  tender  mercies  of  selection. 
No  orthogenetic  line  of  descent  can  persist  in  a  direction 
not  adaptive,  that  is,  not  fit,  and  certainly  no  present-day 
biologist  is  ready  to  fall  back  on  the  long  deserted  stand- 
point of  teleology  and  ascribe  to  heterogenesis  or  ortho- 
genesis an  auto-determination  toward  adaptiveness  and 


376  DARWINISM   TO-DAY. 

fitness.  Modification  and  development  I  may  have  been 
proved  to  occur  along  determinate  lines  without  the  aid  of 
natural  selection.  I  believe  they  have.  But  such  develop- 
ment cannot  have  an  aim;  it  cannot  be  assumed  to  be 
directed  toward  advance;  there  is  no  independent  progress 
upward,  i.  e.,  toward  higher  specialisation.  At  least,  there 
is  no  scientific  proof  of  any  such  capacity  in  organisms. 
Natural  selection 8  remains  the  one  causo-mechanical  ex- 
planation of  the  large  and  general  progress  toward  fitness  ; 
the  movement  toward  specialisation;  that  is,  descent  as  we 
know  it. 

But  what  Darwinism  does  not  do  is  to  explain  the  begin- 
nings of  change,  the  modifications  in  indifferent  characters 
An  explanation  and  in  indifferent  directions.     And  all  this  is 
of  Sang6?  iringS  tremendously  important,  for  there  are  among 
needed,  animals  and  plants  hosts  of  existent  indifferent 

characters,  and  many  apparently  indifferent  directions  of 
specialisation.  As  to  the  obvious  necessity  of  beginnings 
nothing  need  be  said.  What  is  needed,  then,  is  a  satisfactory 
explanation  of  the  pre-useful  and  pre-hurtful  stages  in  the 
modifications  of  organisms :  an  explanation  to  relieve  Dar- 
winism of  its  necessity  of  asking  natural  selection  to  find 
in  the  fluctuating  individual  variations  a  handle  for  its 
action;  an  explanation  of  how  there  ever  comes  to  be  a 
handle  of  advantage  or  disadvantage  of  life-and-death- 
determining  degree.  With  such  an  explanation  in  our 
possession — and  whether  any  one  or  more  of  the  various 
theories  proposed  to  fill  this  need,  such  as  Eimerian 
orthogenesis,  de  Vriesian  heterogenesis,  Rouxian  battle  of 
the  parts,  or  Weismannian  germinal  selection,  etc.,  give 
us  this  explanation,  may  be  left  for  the  moment  undebated 
— with  such  a  satisfactory  explanation,  I  say,  once  in  our 
hands,  we  may  depend  with  confidence  on  natural  selection 
to  do  the  rest  of  the  work  called  for  by  the  great  theory 
of  descent.  Among  all  the  divergent  lines  of  development 


DARWINISM'S   PRESENT   STANDING,  377 

and  change,  instituted  by  this  agent  of  beginnings,  natural 
selection  will  choose  those  to  persist  by  saying  No  to  those 
that  may  not.  And  the  result  is  organic  evolution. 

But  all  this  is  equivalent  to  saying  that  there  are  other 

important  factors  in  descent  than  selection,  and  that  as  to 

the  beginnings  of  descent  —  and  this  is  species- 

The  causes  of  . 

variation  and  the  forming  —  these  other  factors  are  the  more  im- 
meansofsegre-  portant  ones.  Which  I  believe  is  true.  The 

gation,  the  chief    J 

factors  in  spe-  causes  of  variation  and  the  means  of  segrega- 
cies-forming,  ^Qn  Qr  isoiatjon  are  the  chjef  factOrs  in  actual 


species-  forming.  Certainly  the  mutations  theory  is  not  yet 
ready  to  offer  itself  as  an  explanation  of  adaptation,  how- 
ever confidently  it  may  claim  to  be  enrolled  among  species- 
forming  factors.  The  very  same  objections  that  have  served 
to  topple  down  selection  from  its  high  seat  of  honour,  can  be 
directed  immediately  and  effectively  against  this  latest  claim- 
ant for  recognition  as  the  Great  Cause  of  descent.  Nor  can 
geographical  isolation  explain  modification  where  adaptation 
is  included.  Nor  can  Lamarck's  beautiful  explanation  of 
adaptation  claim  validity,  until  the  actuality  of  its  funda- 
mental postulate,  the  carrying  over  of  ontogenic  acquire- 
ments into  phylogeny,  be  proved.  And  so  with  Buffon  and 
St.  Hilaire's  influence  of  the  ambient  medium,  and  Eimer's 
modifying  factors.  Nor  can  any  Nagelian  automatic  per- 
fecting principle  hold  our  suffrage  for  a  moment  unless  we 
stand  with  theologists  on  the  insecure  basis  of  teleology. 

No,   let  no   ambitious   student  hesitate   to   take   up  the 
search  for  the  truth  about  evolution  from  the  notion  that 

The  unknown     biol°gy   is   a   read  book'      The   "Origin  of    Spe- 

factorsofevoln-  cies"  was  the  first  opening  of  the  book  —  that 
the  world  recognised  at  least;  poor  Lamarck 
opened  the  book  but  could  not  make  the  world  read  in  it  — 
and  that  time  when  it  shall  be  closed  because  read  through 
is  too  far  away  even  to  speculate  about.  With  Osborn  4  let 
us  join  the  believers  in  the  "unknown  factors  in  evolution."" 


378  DARWINISM   TO-DAY. 

Let  us  begin  our  motto  with  Ignoramus,  but  never  follow 
it  with  Ignoribimus. 

Now  if  we  do  not  know,  but  want  to  know,  and  are  willing 
to  make  an  attempt  toward  knowing,  where  shall  our  energy 
Prime  needs  °^  exP^orati°n  an^  discovery  be  first  directed?  * 
of  evolution  To  what  particular  points  or  aspects  of  the 
causes-of-evolution  problem  shall  we  give  our 
first  attention,  what  fields  of  study  first  invade  ?  What,  in  a 
word,  is  the  principal  desideratum  in  present-day  investiga- 
tion of  evolution?  I  should  answer,  the  intensive  study  of 
•variability.  Not  alone  of  the  statics  of  variation  but  of  its 
dynamics.  Indeed,  above  all  its  dynamics.  The  experimental 
study  of  the  stimuli,  external  and  internal,  the  influences, 
extrinsic  and  intrinsic,  which  are  the  factors  and  causes  of 
variation, — this  is  the  great  desideratum ;  this  the  crying  call 
to  the  evolution  student.  Experiment  in  variation  study 
includes  controlled  modification  of  ontogeny  (experimental 
development)  and  controlled  modification  of  phylogeny 
(pedigreed  breeding).  In  the  study  of  variation  statics, 
biometry  is  the  greatest  advance  in  modern  methods,  and 
the  essential  basis  of  biometric  study,  namely,  quantitative 
and  statistical  data,  must  have  its  part  in  the  investigation 
of  variation  dynamics.  But  in  entering  the  realm  of  the 
causal  study  of  variability,  "we  must  not,"  as  Roux  has 
clearly  pointed  out,  "conceal  from  ourselves  the  fact  that 
the  causal  investigation  of  organism  is  one  of  the  most 
difficult,  if  not  the  most  difficult,  problem  which  the  human 
intellect  has  attempted  to  solve,  and  that  this  investigation, 
like  every  causal  science,  can  never  reach  completeness, 
since  every  new  cause  ascertained  only  gives  rise  to  fresh 
•questions  concerning  the  cause  of  this  cause." 

I  believe  that  the  neglect  on  the  part  of  the  selectionists  to 
pay  sufficient  attention  to  the  origin  and  causes  of  the  varia- 
tion which  is  such  an  indispensable  basis  of  their  theory,  has 
teen  one  of  the  most  obvious  reasons  for  the  present  strong 


DARWINISM'S   PRESENT   STANDING.  379 

reaction  against  the  selection  theories.     Thankfully  accept- 
ing the  bricks  and  stones  handed  to  them  they  have  builded 
Neglect  of        a  house  of  great  beauty :  but  with   stones  of 
attention  to  the    Different  shape  a  house  of  quite  different  ap- 

causes  of  varia- 
tion, pearance  might  have  been  built.     Is  it  not  a 

cause  for  wonder  that  the  selection  masons  have  not  been 
more  inquisitive  concerning  the  whence  and  why  of  this 
magical  supply  of  just  the  needed  sort  of  material  at  just  the 
right  time?  As  a  matter  of  fact,  Darwin  himself  gave 
serious  attention  to  the  origin  of  his  always-ready  varia- 
tions, but  his  tremendous  undertaking  was  too  nearly  super- 
human already  to  permit  him  to  add  to  it  an  adequate 
attention  to  the  problem  of  causes.  But  that  same  excuse 
does  not  attach  to  his  followers.  And  it  is,  I  repeat,  largely 
this  neglect  to  strive  to  penetrate  the  so-far  unrent  veil  of 
obscurity  lying  over  the  beginnings  of  species  change  that 
has  contributed  to  the  growing  revolt  against  the  Allmacht 
of  the  selection  dogma.  Who  would  in  these  days  have  a 
following  for  his  explanation  of  species  origin  must  include 
in  his  theory  some  fairly  satisfying  explanation  of  the  first 
visible  beginnings  of  modification. 

Then,  after  the  explanation  of  the  why  and  how  of  varia- 
bility,  comes  the  necessity  of  explaining  the  cumulation  of 

this  variability  along  certain  lines,  the  first  visi- 
tion°cumulated~?  ^le  issuance  of  these  lines  being  as  species,  and 

later  becoming  more  and  more  pronounced  as 
courses  of  descent.  This  explanation  has  got  to  begin  lower 
down  in  phyletic  history  than  natural  selection  can  begin. 
Before  ever  there  can  be  utility  and  advantage  there  must 
have  come  about  a  certain  degree  of  heaping  up,  of  cumu- 
lating, of  intensifying  variations.  What  are  these  factors? 
They  are  possibly  only  two:  (i)  orthogenetic  or  deter- 
minate variation  as  the  outcome  of  plasm  preformation  or 
of  epigenetic  influences,  and  (2)  the  segregation  of  similar 
variations  by  physiologic  or  topographic  conditions.  Hence, 


380  DARWINISM   TO-DAY. 

next  to  the  cause  or  origin  of  variability  the  great  desider- 
atum is  a  knowledge  of  the  means  of  cumulating  and  direct- 
ing variability.  And  both  these  great  fundamental  needs 
of  a  satisfactory  understanding  of  organic  evolution  seem 
to  me  to  be  wholly  unreferred  to  in  the  theory  of  natural 
selection.  To  be  sure  the  control  and  cumulation  of  such 
large  differences  among  organisms  and  species  as  are  posi- 
tively sufficient  to  determine  the  saving  or  the  loss  of  life 
are  explicable  by  selection.  And  this  factor  is  sooner  or  later 
in  any  phyletic  history  bound  to  step  in  and  probably 
be  the  dominant  one.  But  a  species,  or  a  character,  will 
always  have  a  longer  or  shorter  preselective  existence  and 
history,  and  it  is  precisely  these  days  before  the  Inqui- 
sition of  which  we  demand  information.  For  of  one  thing 
we  are  now  certain,  and  that  is,  that  evolution  and  the  origin 
of  species  have  both  their  beginnings  and  a  certain  period 
of  history  before  the  day  of  the  coming  of  the  Grand 
Inquisitor,  selection. 

Finally  there  is  still  another  desideratum  and  one  whose 
seeking  will  carry  us  into  dangerous  country.  For  while 
there  may  be  and  are  selectionists  who  might  allow  us  to 
fumble  about  in  the  darkness  of  preselective  time  for  first 
causes,  there  is  probably  none  who  will  allow  us  to  ques- 
tion his  right  to  explain  that  other  element  in  evolution  be- 
sides species  transformation,  namely,  adaptation,  or,  as  the 
Germans  untranslatably  put  it,  Zweckmassigkeit.  But  by 
no  means  all  biologists  6  find  in  natural  selection  a  sufficient 
explanation  of  adaptation. 

In  the  visible  expression  of  organic  evolution  are  two 
chief  elements,  one  the  variety  of  life  kinds,  the  existence  of 
species,  the  reality  of  lines  of  descent;  and  the 
need  of  explain-  other  the  adaptedness  and  adaptiveness  of  these 
ing  adaptation,  life  km(js.  The  varieties  of  organic  kinds  show 
themselves  adapted  in  structure  and  function  to  the  varie- 
ties of  environment  and  life-conditions.  Hence,  the  task 


DARWINISM'S   PRESENT   STANDING.  3Sl 

of  an  evolution  explanation  is  a  double  one ;  it  must  explain 
not  only  diversity  or  variety  in  life,  but  adaptive  diversity 
or  variety.  And  there  is  no  gainsaying  to  the  selection 
explanation  its  claim  to  stand  among  all  proposed  explana- 
tions of  adaptation  as  that  one  least  shaken  by  the  critical 
attack  of  its  adversaries.  However  mightily  the  scientific 
imagination  must  exert  itself  to  deliver  certain  difficult 
cases  into  the  hands  of  selection,  and  however  sophisticated 
and  lawyer-like  the  argument  from  the  selection  side  may 
be  for  any  single  refractory  example,  the  fact  remains  that 
the  selectionist  seems  to  be  able  to  stretch  his  explanation 
to  fit  all  adaptations  with  less  danger  of  finding  it  brought 
up  against  positive  adverse  facts  than  is  possible  to  the 
champion  of  any  other  so  far  proposed  explanation.  The 
explanation  of  adaptation  by  natural  selection  steers  wide 
of  teleology  on  one  hand  and  of  unproved  assumptions  con- 
cerning heredity  on  the  other.  The  protoplasmic  conscious- 
ness of  Cope  and  the  automatic  perfecting  principle  of 
Nageli  and  those  of  his  manner  of  explanation,  are  only 
indirect  ways  of  attributing  to  natural  forces  visions  and 
anticipations  of  what  does  not  yet  exist ;  while  the  influence 
of  the  ambient  medium  of  St.  Hilaire  and  of  the  extrinsic 
factors  of  Eimer,  and  the  impressing  photographically  on 
the  species  and  the  carrying  over  into  phylogeny,  with 
approximate  identity,  of  characteristics  and  modifications 
acquired  ontogenetically  by  the  individual  as  a  result  of 
functional  stimulation — all  these  are  assumptions  not  only 
apparently  unproved,  but  in  the  light  of  our  present 
knowledge  of  the  mechanism  of  heredity  seemingly  un- 
provable. 

Yet  the  explanation  of  species  transformation  and  of 
adaptation  by  the  introduction  into  phylogeny  of  modifica- 
tions (reaction  effects)  arising  in  the  individual  during  its 
ontogeny,  has  to  its  credit  a  certain  logical  proof,  or 
basis,  which  has  great  validity  in  my  mind,  and  yet  which 


382  DARWINISM   TO-DAY. 

has  enjoyed  little  general  recognition  and  almost  no  em- 
phasis from  supporters  of  Lamarckism  or  neo-Lamarckism. 
As  the  great  strength  of  the  natural  selection  explanation  of 
species-change  and  adaptation  lies  precisely  in  the  logical 
nature  of  its  premises  and  conclusions  rather  than  on  scien- 
tific observation  and  experiment,7  it  certainly  is  not  unfair 
to  emphasise  any  similar  kind  of  proof  tending  to  support 
the  Lamarckian  type  of  explanation. 

The  logical  proof  that  I  refer  to  is  simply  this :  It  is  a 

universally  admitted  fact  that  environment  and  functional 

A  logical  proof  stimulation  can  and  do  modify  organisms  dur- 

for  the  introdic-    .  «     .       ...     . 

tion  into  phylog-  lng  their  lifetime,   and   that   this   modification 

eny  of  adaptive  js  usually  plainly  adaptive.  It  is  also  an 
ontogenetic 

changes.  admitted  fact  that  species  differences  or  modi- 

fications are  often  identical  with  these  ontogenetic  modifica- 
tions. That  is,  that  under  similar  environment  or  life 
conditions  species  modification  often  follows  the  same  lines 
as  ontogenetic  or  individual  modification.  Now  when  we 
recall  the  possibilities  of  the  hosts  of  ways  in  which  the 
necessities  of  adaptation  to  varying  environment  might  be 
met  by  selection  among  nearly  infinite  fortuitous  variations, 
and  yet  see  that  exactly  that  means  or  line  or  kind  of  adapt- 
ive change  occurs,  which  in  the  case  of  the  individual  is 
plainly  and  confessedly  a  direct  personal  adaptive  reaction 
to  varying  environment,  is  it  not  the  logical  conclusion  that 
the  species  change  and  adaptation  is  derived,  not  by  the 
chance  appearance  of  the  needed  variation,  but  by  the  com- 
pelled or  determined  appearance  of  this  variation  ?  In  other 
words  when  species  differences  and  adaptations  are  identical 
with  differences  and  modifications  readily  directly  produci- 
ble in  the  individual  by  varying  environment,  are  we  not 
justified,  on  the  basis  of  logical  deduction,  to  assume  the 
transmutation  of  ontogenetic  acquirements  into  phyletic 
acquirements,  even  though  we  are  as  yet  ignorant  of  the 
physico-chemical  or  vital  mechanism  capable  of  effecting  the 


DARWINISM'S   PRESENT    STANDING.  383 

carrying  over?  Has  natural  selection's  claimed  capacity  ta 
effect  species  change,  unseen  by  observer,  untested  by  exper- 
imenter, any  better  or  even  other  proof  of  actuality  than 
that  just  offered  on  behalf  of  species  modification  as  a  direct 
result  of  the  stimulus  of  varying  environment  and  func- 
tional exercise?  I  cannot  see  that  it  has. 

And  this  kind  of  argument,  based  half  on  observed  facts 

and  half  on  deduction,  may  be  extended  even  farther  on 

behalf  of  the  theory  that  species  change  is  the 

The  same  kind  J  ,•  • 

of  proof  for  non-  direct  reaction  to  environmental  conditions.. 
adaptive  change,  For  there  are  many  ontOgenetic  variations  pro- 
duced directly  in  response  to  environment  that  are  not 
plainly  adaptive;  many,  indeed,  between  which  and  the 
environmental  conditions  that  produce  them  no  reasonable 
relation  is  apparent;  no  relation,  that  is,  that  would  be  ex- 
actly expected  or  could  be  foretold  until  empirically  deter- 
mined. In  other  words,  many  apparently  non-significant 
ontogenetic  differences  or  variations  appear  as  direct  result 
of  environmental  influence  or  stimulus.  For  example,  indi- 
viduals of  certain  species  of  the  Crustacean  phyllopod  genus 
Artemia  show  marked  structural  differences  when  grown 
in  salt  water  of  varying  density.  These  differences  are  in 
the  size  and  shape  of  the  plate-like  lateral  gills,  the  seg- 
mentation of  the  post-abdomen,  the  length  of  the  caudal 
flaps  (telson)  and  the  hairiness  of  these  flaps.  The  size  of 
the  whole  body  is  also  affected,  individuals  developing  in 
water  of  higher  density  being  markedly  smaller  than  those 
which  have  been  grown  in  less  dense  water.  Now  of  all 
these  differences  only  two  seem  to  have  what  I  call  a  rea- 
sonable relation  to  the  environmental  differences.  The  in- 
creased proportional  size  of  the  gills  shown  by  the  Artemias 
grown  in  denser  water  appears  to  be  a  regulatory  change 
connected  with  the  smaller  amount  of  oxygen  in  the  water,, 
and  the  decreased  size  of  the  body  may  similarly  be  con- 
ceived by  some  to  be  an  expected  concomitant  of  the: 


384  DARWINISM   TO-DAY. 

denser  water  condition.  But  what  of  the  extra  abdominal 
segment,  the  longer  telson  projections  and  their  increased 
hairiness,  all  of  which  as  shown  by  Schmankewitsch  8  (how- 
ever mistakenly  this  investigator  may  have  interpreted  his 
results  as  examples  of  actual  species  modification)  and 
Anikin  9  for  Artemia  salina  and  by  the  writer10  for  Artemia 
franciscanus,  are  the  ontogenetic  differences  that  varying 
density  of  salt  water  actually  produces  in  individuals  of  a 
single  Artemia  species.  These  differences,  these  variations, 
are  of  the  sort  that  I  am  calling  non-significant,  non-adapt- 
ive, non-reasonable.  They  would  not  be  prophesied;  they 
seem  to  have  no  reasonable  correlation  with  the  causes 
which  produce  them.  But  they  are  actually  the  results  or 
effects  of  determined  proximate  causes  which  are  extrinsic 
or  environmental.  If  now  the  logical  argument  (based  on 
identity  of  adaptive  modification  in  individuals  and  in  spe- 
cies) for  the  transmutation  of  ontogenetic  changes  into 
phyletic  changes  has  any  validity,  then  these  non-adaptive, 
indifferent  modifications  may  be  transmuted  as  well  as  the 
adaptive  ones,  and  thus  hosts  of  trivial,  non-adaptive  indif- 
ferent species  differences  be  explained  on  this  Lamarcko- 
Eimerian  basis  as  well  as  the  obviously  adaptive  modifica- 
tions. But  I  am  not  insisting  on  this  sort  of  argument  too 
strongly.  It  is  exactly  the  sort  of  argument  upon  which  the 
theory  of  natural  selection  chiefly  rests,  and  I  have  cer- 
tainly tried  to  make  evident  in  this  book  my  belief  in  the 
danger  of  the  substitution  of  this  sort  of  logical  or  meta- 
physical basis  of  belief  in  a  theory  for  a  scientific  basis  of 
observation  and  experiment. 

Finally,  let  us  ask  ourselves  why  we  have  adopted  the 

common  belief  that  our  search  for  a  cause  of  variability  is  a 

A  suggestion     search  for  some  so  far  unknown,  some  quite 

concerning  the     new  f actOr  or  force  in  biology  ?    May  it  not  be 

canseofvana- 

tion.  that  the  factor  is   already   familiar  to   us ;  so 

familiar  indeed  perhaps  that  we  are  esteeming  it  too  simple 


DARWINISM'S   PRESENT   STANDING.  385 

and  too  obvious  to  play  the  role  of  the  Great  Desideratum, 
a  causal  factor  of  variability. 

When  one  attempts  to  picture  the  process  of  the  making 
of  a  new  individual,  and  follows  the  complex  phenomena  of 
fecundation,  of  embryology,  and  post-embryonic  develop- 
ment, is  it  not  impossible  to  conceive  of  the  production  of 
two  identical  individuals  ?  In  all  the  course  of  this  develop- 
ment, from  the  first  cleavage  of  the  fertilised  egg-cell  on, 
it  is  practically  impossible  to  repeat  processes  absolutely 
identically,  hence  to  produce  absolutely  identical  organs, 
parts,  cells.  Now  the  germ-cells  have  their  very  origin  in 
a  repeated  complex  process,  mitotic  cell  division;  they  are 
produced  as  nearly  alike  as  possible,  but  it  is  not  possible 
to  make  them  absolutely  identical. 

Development,  whether  largely  epigenetic  or  largely  evo- 
lutionary, depends  at  least  partly  (probably  largely)  on  the 
physical,  i.  e.,  structural,  character  of  the  germ-cells.  Slight 
differences  in  the  germ-cells  then  would  lead  to  considera- 
ble differences  in  the  fully  developed  organ.  If  the  differ- 
ences in  the  germ-cells  happened,  as  would  occasionally  or 
rarely  be  the  case,  to  be  considerable,  then  the  differences  in 
the  adults  would  be  very  considerable  (mutations,  sports, 
monsters,  etc.).  We  know  enough  of  the  complex  and 
epigenetic  character  of  ontogeny  to  see  plainly  that  identity 
among  individuals,  even  of  the  same  brood,  is  impossible. 

Variation,  then,  seems  the  necessary,  the  absolutely  un- 
avoidable outcome  of  the  conditions  to  which  the  developing 
individual  is  exposed.  Indeed,  all  the  individuals  of  a 
species  might  start  (as  fertilised  eggs)  exactly  alike,  and 
yet  I  cannot  see  how  any  two  could  come  out  alike.  The 
inevitable  slight  differences  in  position,  and  hence  in  nutri- 
tion, in  the  results  of  the  host  of  dividing  and  folding,  in- 
vaginating  and  evaginating  processes,  the  relations  of  each 
individual,  whether  in  the  mother's  body  or  out  of  it,  to 
everything  else  outside  -of  itself — all  these  are  conditions 


386  DARWINISM   TO-DAY. 

bound  to  vary  a  little  between  any  two  individuals.  And  as 
we  know  from  the  facts  of  experimental  embryology  that 
development  is,  partly  at  least,  epigenetic  in  character,  i.e., 
depends  on  and  is  influenced  by  external  factors,  this  in- 
evitable variation  in  influencing  conditions  is  bound  to  pro- 
duce variations  in  the  individuals. 

Is  there,  indeed,  any  need  at  all  for  assuming  (i)  any 
mysterious  "tendency"  of  the  germ-plasm  to  vary?  and  (2) 
that  the  individual  (continuous)  variation  depends  wholly  on 
germ-plasm  structure?  Why  cannot  the  simple  fluctuating 
or  Darwinian  variations  be  chiefly  the  result  of  the  inevitable 
variation  in  the  epigenetic  factors,  which,  when  not  intruded 
on  by  exceptional  disturbances,  would  themselves  follow  the 
"law  of  error"  and  hence  produce  "law  of  error"  variabil- 
ity? All  normal  swingings  of  the  variation  pendulum  in 
any  part  or  character,  between  long  and  short,  large  and 
small,  round  and  angular,  smooth  and  rough,  etc.,  etc., 
would  result  from  the  normal  variation  of  the  processes ;  the 
larger  (extremes  of  range)  variations  being  the  fewer  be- 
cause the  larger  (extremes  of  range)  variations  in  the 
ontogenetic  processes  would  be  the  fewer.  Exceptionally 
large  epigenetic  variations  would  produce  exceptionally 
large  variations  in  the  individual — sports,  mutations. 

Klebs,11  as  a  result  of  his  masterly  experimental  studies 
on  modifications  of  plant  development,  comes  to  the 
conclusion  that  the  only  proved  causes  of  variation  are 
extrinsic  influences  stimulating,  working  through,  or  com- 
bined with,  intrinsic  conditions  (not  vitalistic,  but  physico- 
chemical).  Similarly,  Tower,12  from  his  protracted  studies 
on  the  variations  in  certain  insects,  concludes  that  all  these 
variations  are  caused  by  external  stimuli  working  on  the 
germ-plasm. 

If  variation  is  thus  simply  the  wholly  natural  and  un- 
avoidable effect 1S  of  this  inevitable  non-identity  of  vital 
process  and  environmental  condition,  why  does  not  evolution 


DARWINISM'S   PRESENT   STANDING.  3^7 

possess  in  this  state  of  affairs  the  much  sought  for,  often 
postulated,  all-necessary,  automatic  modifying  principle  an- 
tedating and  preceding  selection  which   must 

A  determinate 

though  not  pur-  effect  change,  determinate  though  not  purpose- 
poseful  change,  ful  ?  Nageli's  automatic  perfecting  principle  is 
an  impossibility  to  the  thorough-going  evolutionist  seeking 
for  a  causo-mechanical  explanation  of  change.  But  an 
automatic  modifying  principle  which  results  in  determinate 
or  purposive  change,  that  is,  in  the  change  needed  as  the 
indispensable  basis  for  the  upbuilding  of  the  great  fabric  of 
species  diversity  and  descent ;  is  not  that  the  very  thing  pro- 
vided by  the  simple  physical  or  mechanical  impossibility  of 
perfect  identity  between  process  and  environment  in  the  case 
of  one  individual  and  process  and  environment  in  the  case 
of  any  other  ?  It  seems  so  to  me. 

But  I  do  not  know.  Nor  in  the  present  state  of  our  knowl- 
edge does  any  one  know,  nor  will  any  one  know  until,  as 
Brooks  14  says  of  another  problem,  we  find  out.  We  are 
ignorant;  terribly,  immensely  ignorant.  And  our  work  is, 
to  learn.  To  observe,  to  experiment,  to  tabulate,  to  induce, 
to  deduce.  Biology  was  never  a  clearer  or  more  inviting 
field  for  fascinating,  joyful,  hopeful  work.  To  question  life 
by  new  methods,  from  new  angles,  on  closer  terms,  under 
more  precise  conditions  of  control ;  this  is  the  requirement 
and  the  opportunity  of  the  biologist  of  to-day.  May  his 
generation  hear  some  whisper  from  the  Sphinx ! 

APPENDIX. 

1  One  of  the  most  serious  and  detailed  critical  analyses  of  the 
selection  theory,  resulting  in  conclusions  totally  antagonistic  to  Dar- 
Wigand's  criti-  winism,  is  that  of  the  Marburg  botanist,  Prof.  Albert 
cismoftheselec-  Wigand,  composing  the  three  volumes  entitled  "Der 
tion  theories.  Darwinismus  und  die  Naturforschung  Newtons  und 
Cuviers"  (Vol.  I,  1874;  Vol.  II,  1876;  Vol.  Ill,  1877).  From  the 
"Announcements"  at  the  beginning  of  each  volume  I  quote  as 
follows : 


388  DARWINISM   TO-DAY. 

From  Vol.  I.  "Die  hier  dargebotene  Kritik  der  Darwin'schen 
Lehre  weist  zunachst  durch  eingehende  Priifung  der  hierher  ge- 
horigen  naturhistorischen  Thatsachen  nach,  dass  weder  die  Voraus- 
setzungen,  von  denen  die  Theorie  ausgeht,  noch  ihre  Consequenzen 
mit  der  wirklichen  Natur  iibereinstimmen,  dass  sie  demnach  den 
Anforderungen  an  eine  wissenschaftliche  Hypothese  nicht  entspricht. 
Vielmehr  erweist  sich  dieselbe  als  eine  philosophische  Speculation, 
welche  nicht  nur  die  unserer  Naturerkenntniss  vorgezeichneten 
Grenzen  uberschreitet,  sondern  vor  Allem  die  wichtigsten  Grundsatze 
der  waiiren  Forschung,  wie  sie  durch  die  grossen  Meister  aufgestellt 
und  in  der  bisherigen  Entwickelung  der  Naturwissenschaft  allgemein 
anerkannt  und  unbedingt  maassgebend  gewesen  sind,  insbesondere 
die  Principien  der  Causalitat  und  der  organischen  Entwickelung,  aufs 
grobste  verleugnet.  Demnach  erkennt  das  vorliegende  Werk  seine 
Hauptaufgabe  gerade  darin,  der  bis  dahin  befolgten  Forschungsweise 
gegeniiber  jener  neuesten  Naturphilosophie  ihr  Recht  zu  wahren." 

From  Vol.  II.  "Vermittelst  der  hierdurch  gewonnenen  Kriterien 
gelangt  die  Untersuchung  in  Betreff  des  Darwinismus  zu  fol- 
gendem  Ergebnis :  Derselbe  geht  nicht  bloss  von  falschen  Voraus- 
setzungen  aus,  erweist  sich  nicht  nur  unfahig  in  Beziehung  auf  die 
versprochenen  Leistungen,  ist  nicht  nur  verfehlt  durch  die  princi- 
pielle  Unmoglichkeit  seiner  Aufgabe,  ist  nicht  nur  eine  der  Natur- 
forschung  fremdartige,  rein  speculative  Operation,  sondern  indem 
derselbe  das  Princip  der  Causalitat  und  Entwickelung  mit  dem 
Zufall  und  der  Teleologie  als  Erklarungsgrunde  vertauscht,  erscheint 
er  als  eine  der  Naturforschung  in  ihrer  Fundamentalmaxime  wider- 
sprechende,  darum  dieselbe  geradezu  gefahrdende  Verirrung,  um 
so  mehr  als  er  unter  ihrer  Maske  auftritt.  Der  Darwinismus  ist 
einer  jener  Versuche,  welche  im  Namen  der  Naturforschung  die 
Naturforschung  verderben." 

From  Vol.  III.  "Der  vorliegende  dritte  Band,  mit  welchem  dieses 
Werk  abschliesst,  hat  zum  Gegenstand  nicht  die  dem  Darwinismus 
zu  Grunde  liegende  Theorie,  sondern  die  concrete  Gestalt,  in  welcher 
derselbe  als  eine  fur  unsere  Zeit  charakteristische  culturhistorische 
Thatsache  in  die  Erscheinung  tritt.  Insbesondere  wird  versucht, 
ein  Bild  von  der  Darwin'schen  Schule  als  der  Gesammtheit  der  die 
Transmutationstheorie  vertretenden  Auctoren  und  von  der  Art  und 
Weise,  wie  sich  die  letztere  im  Lichte  ihrer  Bekenner  darstellt,  zu 
entwerfen.  Hierbei  ergibt  sich,  dass  der  Darwinismus  mehr  in  einer 
ziellosen  Zeitstromung  und  in  einer  wissenschaftlich  nicht  motivirten 
Stimmung  der  Geister  als  in  einer  bestimmt  zu  formulirenden  Lehre 
besteht,  und  dass  derselbe  bereits  in  seinem  eigenen  Lager  in  alien 
wesentlichen  Punkten  wissenschaftlich  iiberwunden  ist,  und  zwar  in 
solcher  Weise,  dass  in  den  widerstreitenden  Ansichten  der  Darwin- 


DARWINISM'S   PRESENT   STANDING.  389 

ianer  doch  zugleich  der  Keim  fur  die  allein  richtige  Auffassung  der 
organischen  Natur,  wenn  auch  grossentheils  unklar  und  unbewusst, 
verborgen  liegt." 

A  special  answer  to  this  exhaustive  pleading  of  Wigand  is  offered 
by  H.  Spitzer  in  his  "Beitrage  zur  Descendenztheorie  und  zur  Metho- 
dologie  der  Naturwissenschaft,"  1886. 

2  However,    there    still    exist,    especially    in    England,    thorough- 
going Darwinians  who  see  nothing  serious  in  all  this  criticism  of 

Lankester's  their  great  compatriot's  explanation  of  the  origin  of 
upholding  of  species.  Lankester,  one  of  the  most  prominent  of 
Darwinism,  English  naturalists,  said  at  York,  last  August  (1906), 

in  his  inaugural  address  as  president  of  the  British  Association  for 
the  Advancement  of  Science :  "Under  the  title  'Darwinism'  it  is  con- 
venient to  designate  the  various  work  of  biologists  tending  to  estab- 
lish, develop  or  modify  Mr.  Darwin's  great  theory  of  the  origin  of 
species.  In  looking  back  over  twenty-five  years  it  seems  to  me  that 
we  must  say  that  the  conclusions  of  Darwin  as  to  the  origin  of 
species  by  the  survival  of  selected  races  in  the  struggle  for  exist- 
ence are  more  firmly  established  than  ever.  And  this  because  there 
have  been  many  attempts  to  gravely  tamper  with  essential  parts 
of  the  fabric  as  he  left  it,  and  even  to  substitute  conceptions  for 
those  which  he  endeavoured  to  establish,  at  variance  with  his 
conclusions.  These  attempts  must,  I  think,  be  considered  as  having 
failed." 

3  "Physiologic   facts   concerning  the   origin   of  species   in   nature 
were  unknown   in  the  time  of  Darwin.     It  was   a   happy  idea   to 

De  Vries's  dis-  cnoose  the  experience  of  the  breeders  in  the  produc- 
cnssion  of  species-  tion  of  new  varieties,  as  a  base  on  which  to  build  an 
forming  by  explanation  of  the  processes  of  nature.  In  my  opinion 

Darwin  was  quite  right,  and  he  has  succeeded  in  giv- 
ing the  desired  proof.  But  the  basis  was  a  frail  one,  and  would  not 
stand  too  close  an  examination.  Of  this  Darwin  was  always  well 
aware.  He  has  been  prudent  to  the  utmost,  leaving  many  points 
undecided,  and  among  them  especially  the  range  of  validity  of  his 
several  arguments.  Unfortunately  this  prudence  has  not  been 
adopted  by  his  followers.  Without  sufficient  warrant  they  have  laid 
stress  on  one  phase  of  the  problem,  quite  overlooking  the  others. 
Wallace  has  even  gone  so  far  in  his  zeal  and  ardent  veneration  for 
Darwin,  as  to  describe  as  Darwinism  some  things,  which,  in  my 
opinion,  had  never  been  a  part  of  Darwin's  conceptions. 

"The  experience  of  the  breeders  was  quite  inadequate  to  the 
use  which  Darwin  made  of  it.  It  was  neither  scientific,  nor  critically 
accurate.  Laws  of  variation  were  barely  conjectured;  the  different 
types  of  variability  were  only  imperfectly  distinguished.  The  breed- 


39°  DARWINISM   TO-DAY. 

ers' conception  was  fairly  sufficient  for  practical  purposes,  but  science 
needed  a  clear  understanding  of  the  factors  in  the  general  process 
of  variation.  Repeatedly  Darwin  tried  to  formulate  these  causes, 
but  the  evidence  available  did  not  meet  his  requirements. 

"Quetelet's  law  of  variation  had  not  yet  been  published.  Mendel's 
claim  of  hereditary  units,  for  the  explanation  of  certain  laws  of 
hybrids  discovered  by  him,  was  not  yet  made.  The  clear  distinction 
between  spontaneous  and  sudden  changes,  as  compared  with  the 
ever-present  fluctuating  variations,  is  only  of  late  coming  into  recog- 
nition by  agriculturists.  Innumerable  minor  points  which  go  to  elu- 
cidate the  breeders'  experience,  were  unknown  in  Darwin's  time. 
No  wonder  that  he  made  mistakes,  and  laid  stress  on  modes  of 
descent  which  have  since  been  proved  to  be  of  minor  importance 
or  even  of  doubtful  validity. 

"Notwithstanding  all  these  apparently  unsurmountable  difficulties, 
Darwin  discovered  the  great  principle  which  rules  the  evolution  of 
organisms.  It  is  the  principle  of  natural  selection.  It  is  the  sifting 
out  of  all  organisms  of  minor  worth  through  the  struggle  for  life. 
It  is  only  a  sieve,  and  not  a  force  of  nature,  no  direct  cause  of 
improvement,  as  many  of  Darwin's  adversaries,  and  unfortunately 
many  of  his  followers  also,  have  so  often  asserted.  It  is  only  a 
sieve,  which  decides  which  is  to  live,  and  what  is  to  die.  But  evo- 
lutionary lines  are  of  great  length,  and  the  evolution  of  a  flower,  or 
of  an  insectivorous  plant  is  a  way  with  many  side-paths.  It  is  the 
sieve  that  keeps  evolution  on  the  main  line,  killing  all,  or  nearly 
all  that  try  to  go  in  other  directions.  By  this  means  natural  selec- 
tion is  the  one  directing  cause  of  the  broad  lines  of  evolution. 

"Of  course,  with  the  single  steps  of  evolution  it  has  nothing  to 
do.  Only  after  the  step  has  been  taken,  the  sieve  acts,  eliminating 
the  unfit.  The  problem,  as  to  how  the  individual  steps  are  brought 
about,  is  quite  another  side  of  the  question"  (De  Vries,  "Species 
and  Varieties,"  pp.  4-7,  1905). 

The  distinguished  French  zoologist  (Professor  in  the  University 
of  Paris),  Delage,  leader  among  French  morphologists  and  experi- 
Delage's  esti-  menters,  voices  his  position  concerning  Darwinism  in 
mate  of  selection,  the  following  concise  phrases  ("L'Heredite,"  2d  ed., 
P-  397>  I9°3)  :  "La  selection  naturelle  est  un  principe  admirable  et 
parfaitement  juste.  Tout  le  monde  est  d'accord  aujourd'hui  sur  ce 
point.  Mais  ou  Ton  n'est  pas  d'accord,  c'est  sur  la  limite  de  sa 
puissance  et  sur  la  question  de  savoir  si  elle  peut  engendrer  des 
formes  specifiques  nouvelles.  11  semble  bien  demontrer  aujourd'hui 
qu'elle  ne  le  peut  pas." 

1  "A  study  of  the  recent  discussion  in  the  Contemporary  Review 
between  Spencer  and  Weismann  leads  to  the  conclusion  that  neither 


DARWINISM'S   PRESENT   STANDING.  391 

of  these  acknowledged  leaders  of  biological  thought  supports  his 
position  upon  inductive  evidence.  Each  displays  his  main  force 

Osborn's cham-  *n  destructive  criticism  of  his  opponent;  neither  pre- 
pionship  of  the  sents  his  case  constructively  in  such  a  manner  as  to 
"unknown  factors  carry  conviction  either  to  his  opponent  or  to  others.  In 
of  evolution."  short?  beneath  the  surface  of  fine  controversial  style 
we  discern  these  leaders  respectively  maintaining  as  finally  estab- 
lished theories  which  are  less  grounded  upon  fact  than  upon  the 
logical  improbabilities  of  rival  theories.  Such  a  conclusion  is  deeply 
significant;  to  my  mind  it  marks  a  turning  point  in  the  history  of 
speculation,  for  certainly  we  shall  not  arrest  research  with  any 
evolution  factor  grounded  upon  logic  rather  than  upon  inductive 
demonstration.  A  retrograde  chapter  in  tfie  history  of  science 
would  open  if  we  should  do  so  and  should  accept  as  established 
laws  which  rest  so  largely  upon  negative  reasoning.  .  .  . 

"The  first  step  then  towards  progress  is  the  straightforward  con- 
fession of  the  limits  of  our  knowledge  and  of  our  present  failure 
to  base  either  Lamarckism  or  neo-Darwinism  as  universal  princi- 
ples upon  induction.  The  second  is  the  recognition  that  all  our 
thinking  still  centres  around  the  five  working  hypotheses  which 
have  thus  far  been  proposed;  namely,  those  of  Buffon,  Lamarck,  St. 
Hilaire,  Darwin,  and  Nageli.  Modern  criticism  has  highly  differ- 
entiated, but  not  essentially  altered  these  hypothetical  factors  since 
they  were  originally  conceived.  Darwin's  'survival  of  the  fittest' 
we  may  alone  regard  as  absolutely  demonstrated  as  a  real  factor, 
without  committing  ourselves  as  to  the  'origin  of  fitness.'  The 
third  step  is  to  recognise  that  there  may  be  an  unknown  factor  or 
factors  which  will  cause  quite  as  great  surprise  as  Darwin's."  .  .  . 

"The  general  conclusion  we  reach  from  a  survey  of  the  whole 
field  is,  that  for  Buffon's  and  Lamarck's  factors  we  have  no  theory 
of  heredity,  while  the  original  Darwin  factor,  or  neo-Darwinism, 
offers  an  inadequate  explanation  of  evolution.  If  acquired  varia- 
tions are  transmitted,  there  must  be,  therefore,  some  unknown 
principle  in  heredity ;  if  they  are  not  transmitted,  there  must  be 
some  unknown  factor  in  evolution."  (Osborn.  H.  F.,  "The  Un- 
known Factors  of  Evolution,"  in  Wood's  Holl  Biological  Lectures, 
pp.  79,  80,  81,  98,  and  99,  1894.) 

5  Davenport,  C  B.,  "Animal  Morphology  in  its  Relation  to  Other 
Sciences,"  Congress  of  Arts  and  Sciences,  Vol.  V,  pp.  244-257,  1906. 
In  this  paper  are  pointed  out  in  admirable  manner  the  present- 
moment  problems,  interests,  and  points  of  view  of  evolution  biolo- 
gists. 

*  Henry  de  Varigny,  in  "La  Nature  et  La  Vie,"  1905,  says  that  for 
many  adaptations  "il  n'y  a  pas  a  se  dissimuler  que,  dans  beaucoup 


392  DARWINISM   TO-DAY. 

de  cas,  cette  explication  [of  the  adaptation]  est  purement  verbale; 
nous  constatons  un  resultat.  nous  1'exprimons  en  essayant  de  1'inter- 
preter  ;  mais  le  mecanisme  reste  obscur.  .  .  .  Dans  beaucoup  de  cas, 
I'adaptation  est  un  phenomene  que  Ton  constate  sans  peine  mais 
qui  dans  1'etat  actuel  de  nos  connaissances,  reste  sans  explication" 
(p.  184  and  p.  185). 

Klebs,  Georg,  "Willkiirliche  Entwicklungsanderungen  bei  Pflan- 
zen,"  1903.  An  interesting,  suggestive,  and  valuable  account  of 

Klebs's  conclu-  experiments,  and  their  significance,  on  altering  the 
sion  from  experi-  developmental  phenomena  of  plants.  Although  he  is 
ments  on  plants,  strongly  opposed  to  any  vitalistic  theory  which  attrib- 
utes to  life  an  independence  of  physico-chemical  laws,  Klebs  does 
not  accept  the  Darwinian  explanation  of  adaptiveness.  Darwin 
"betrachtet  die  Zweckmassigkeit  selbst  als  den  wesentlichsten  Faktor 
der  Artbildung,  indem  nach  seiner  Meinung  die  natiirliche  Zucht- 
wahl  aus  der  Menge  der  richtungslos  auftretenden  variationen  nur 
die  zweckmassigkeiten  Merkmale  zur  Ausbildung  und  weiteren 
Entfaltung  bringt.  Daher  stammt  die  friiher  so  verbreitcte  und 
heute  uns  sonderbar  erscheinende  Meinung,  dass  die  Deutung 
eines  Merkmale s  als  eines  zweckm'dssigen  schon  als  eine  Erkldrung 
fur  sein  Entstehen  und  seine  Ausbildung  angenommen  wurde.  Die 
Geltung  der  Darwin'schen  Theorie  muss  seit  den  Arbeiten  Nagelis,. 
de  Vries,  u.  a.  jedenfalls  eingeschrankt  werden.  Das  eigentliche 
Problem  der  Artbildung  muss,  wie  wir  spater  sehen  werden  in 
anderer  Weise,  formuliert  werden"  (p.  3). 

Friedlander  ("Entdeckung  eines  'Atlantischen  Palolo,'  "  etc.,  Biol. 
CentralbL,  Vol.  XXI,  pp.  352-366,  1901)  refers  to  the  Darwinian 
explanation  of  Zweckmassigkeit  as  follows : 

"Der  ganze  Darwinismus  im  weiteren,  also  auch  vordarwin'schen 
Sinne  der  Descendenzhypothese,  mit  oder  ohne  Betonung  der  Selek- 

Priedlander's  tionstheorie,  und  samt  den  allseitig  als  fertig  und 
discussion  of  sicher  festgestellt  gedachten  Stammbaumen  aller  Or- 
adaptation,  ganismen,  wiirde,  wenn  auch  alles  damit  sonst  seine 

Richtigkeit  hatte,  unsere  Gesamterkenntnis  keineswegs  in  so  iiber- 
massigem  Grade  bereichern,  wie  man  friiher  wahnte  und  vor  allem 
nicht  in  dem  Masse,  als  dass  es  sich  lohnte,  auf  die  Herstellung 
der  zudem  immer  problematischen  Stammbaume  sonderliche  Zeit  und 
Miihe  zu  verwenden.  Zweitens  aber  haben  die  neueren  Experimental- 
forschungen  Arten  der  Zweckmassigkeit  an  den  Tag  gebracht,  welche 
aus  rein  logischen  Griinden  durch  die  Selektionstheorie  durchaus 
nicht,  auch  nicht  einmal  scheinbar,  'erklart'  werden  konnen.  Nun 
ist  aber  doch  gerade  die  vermeintliche  'Erklarung'  der  organischen 
Zweckmassigkeit  oder  sogen.  'Anpassungsvollkommenheit'  die 
Hauptstarke  des  eigentlichen  Darwinismus.  Wie  die  Sache  jetzt 


DARWINISM'S   PRESENT   STANDING.  395 

liegt,  miissten  die  Verteidiger  des  Darwinismus  annehmen,  dass  die 
organische  Zweckmassigkeit  zwei  vollkommen  verschiedene  Wurzeln 
habe.  Die  eine  ware  die  alte  Darwin'sche  oder  darwinistische — 
da  namlich,  wo  diese  logischerweise  moglich  ist ;  obwohl  ja  auch 
hier  die  Erklarung  die  nicht  recht  befriedigende  Form  hat,  dass 
gesagt  wird,  die  Zweckmassigkeit  riihre  daher,  dass  die  weniger 
zweckmassigen  Formen  ausgestorben  seien.  Die  zweite  Wurzel  der 
organischen  Zweckmassigkeit,  wie  sie  sich  namentlich  in  den  Selbst- 
regulationserscheinungen  aussert  und  zwar  auch  unter  solchen 
Bedingungen,  die  in  der  freien  Natur  kaum  jemals  vorkommen  und 
daher  fur  das  'Bestehender  Art'  nicht  von  irgend  welcher  Bedeutung- 
sein  konnen — diese  zweite  Wurzel  der  Zweckmassigkeit  ist  der 
eigentliche  Stein  des  Anstosses.  Die  Thatsachen  sind  hartnackig,. 
eine  darwinistische  Scheinerklarung  ist  hier  unmoglich  und  die  an 
sich  doch  so  ausserst  interessanten  Erscheinungen,  sowie  die  ganze 
experimentelle  Forschungsmethode  ist  bei  den  eigentlichen  Dar- 
winisten  nicht  in  gutem  Ansehen ;  aus  dem  sehr  begreiflichen  Grunde, 
weil  jene  Thatsachen  fur  die  betreffende  Richtung  unbequem  sind. 
Eine  Reihe  sicher  festgestellter  Thatsachen  aus  dem  Gebiete  der 
sogen.  Selbstregulation  beweist  also,  dass  es  organische  Zweck- 
massigkeiten  und  obendrein  typische  Beispiele  von  solchen  giebt, 
welche  dem  Darwin'schen  Erklarungsschema  vollkommen  trotzen. 
Nun  aber  hat  die  organische  Zweckmassigkeit  im  ganzen  ein  so 
einheitliches  Geprage,  dass  ein  doppelter  Ursprung  von  vorn  herein 
ausserst  unwahrscheinlich  ist.  Hieraus  folgt  dann  weiter,  dass  die 
darwinistische  Betrachtungsweise  in  der  Wirklichkeit  wahrscheinlich 
auch  in  den  Fallen  nicht  zutrifft,  wo  sie  logisch  wenigstens  die 
Moglichkeit  einer  Erklarung  oder  Quasierklarung  darzubieten 
scheint.  Endlich  aber  sollten  auch  diejenigen,  denen  die  Bedenken 
gegen  die  darwinistischen  Schlussfolgerungen  nicht  recht  eingehen 
wollen,  nachgerade  doch  wenigstens  das  einsehen,  dass  der  Teil  der 
Biologie,  der  sich  allenfalls  im  darwinistischen  Sinne  behandeln 
liesse  oder  doch  in  Sinne  jener  Richtung  nach  Darwin'schen  Prin- 
zipien  behandelt  werden  kann, — dass  dieser  Teil  nur  ein  kleines 
und  vergleichsweise  auch  unwichtiges  Gebiet  umfasst." 

7  Jacques  Loeb,  in  a  recent  address  ("Recent  Development  of 
Biology,"  Congress  of  Arts  and  Sciences,  Vol.  V,  p.  17,  1906),  takes 
this  attitude  toward  the  problem  of  species-forming:  "The  theory 
Loeb's  attitude  of  neredity  of  Mendel  and  de  Vries  is  in  full  har- 
toward  the  prob-  mony  with  the  idea  of  evolution.  The  modern  idea 
lem  of  species-  of  evolution  originated,  as  is  well  known,  with 
forming.  Lamarck,  and  it  is  the  great  merit  of  Darwin  to  have 

revived  this  idea.  It  is,  however,  remarkable  that  none  of  the 
Darwinian  authors  seemed  to  consider  it  necessary  that  the  trans- 


394  DARWINISM   TO-DAY. 

formation  of  species  should  be  the  object  of  direct  observation.  It 
is  generally  understood  in  the  natural  sciences  either  that  direct 
observation  should  form  the  foundation  of  our  conclusions  or 
mathematical  laws,  which  are  derived  from  direct  observations.  This 
rule  was  evidently  considered  superfluous  by  those  writing  on  the 
hypothesis  of  evolution.  Their  scientific  conscience  was  quieted  by 
the  assumption  that  processes  like  that  of  evolution  could  not  be 
directly  observed,  as  they  occurred  too  slowly,  and  that  for  this 
reason  indirect  observations  must  suffice.  I  believe  that  this  lack 
of  direct  observation  explains  the  polemical  character  of  this  liter- 
ature, for  wherever  we  can  base  our  conclusions  upon  direct  obser- 
vations polemics  become  superfluous.  It  was,  therefore,  a  decided 
progress  when  de  Vries  was  able  to  show  that  the  hereditary 
changes  of  forms,  so-called  'mutations,'  can  be  directly  observed,  at 
least  in  certain  groups  of  organisms,  and  secondly,  that  these 
changes  take  place  in  harmony  with  the  idea  that  for  definite 
hereditary  characteristics  definite  determinants,  possibly  in  the  form 
of  chemical  compounds,  must  be  present  in  the  sexual  cells.  It  seems 
to  me  that  the  work  of  Mendel  and  de  Vries  and  their  successors 
marks  the  beginning  of  a  real  theory  of  heredity  and  evolution.  If 
it  is  at  all  possible  to  produce  new  species  artificially,  I  think  that 
the  discoveries  of  Mendel  and  de  Vries  must  be  the  starting  point." 

8  Schmankewitsch,  A.,  Zeitschr.  f.  wiss.  Zool.,  Vol.  XXV,  p.  103, 
1875 ;  also  Zeitschr.  f.  wiss.  Zool,  Vol.  XXIX,  p.  429,  1877. 

*  Adelung,  Zool-Centralbl.,  Vol.  VI,  p.  757,  1899.  (A  review  of 
Anikin's  paper,  which  is  in  Russian.) 

10  Kellogg,  V.   L.,    "A   New   Artemia,   and   Its   Life-Conditions," 
Science,  N.  S.,  Vol.  XXIV,  594-596,  1906. 

11  Klebs,   G.,   "Willkiirliche   Entwickelungsanderungen   bei    Pflan- 
zen,"  1903. 

12  Tower,  W.  L.,  "Evolution  in  Chrysomelid  Beetles  of  the  Genus 
Leptinotarsa,"    Pub.    No.   48,    Carnegie    Institution   of   Washington. 

"The  phenomenon  of  variation  primarily  owes  its  existence  to  the 
fact  that  community  of  descent  and  heredity  tends  to  produce  the 
exact  counterpart  of  the  parent  organisms ;  the  process  of  develop- 
ment, however,  is  not  carried  out  under  absolutely  constant  or  uni- 
form conditions,  but  in  a  world  wherein  there  exist  changing  environ- 
mental states  in  endless  proximity.  This  results  in  the  turning 
aside  in  the  line  of  development  from  the  parental  standard,  per- 
haps ever  so  little  or  only  in  one  character;  but  in  this  we  have 
deviation  or  variation"  (p.  298). 

"In  the  explanation  of  origin  of  variation  in  organisms  the  only 
assumption  we  need  make  is  that  the  original  unit  of  organic  matter 
was  possessed  of  the  attributes  which  characterise  organic  matter 


DARWINISM'S   PRESENT   STANDING.  395 

to-day — motion,  sensation,  growth,  and  reproduction.  This  assump- 
tion cannot  meet  with  any  serious  objection  unless  we  change  our 
ideas  and  definition  of  organic  units.  Granted  the  existence  of  one 
single  organic  unit  endowed  as  above,  there  is  no  reason  for  intro- 
ducing further  complications  by  the  explanation  of  phenomena 
through  undemonstrable  hypotheses,  because  the  fact  of  variation  in 
organic  units  can  be  explained  solely  through  their  existence  in  a 
natural  world  surrounded  by  varying  conditions  of  existence" 
(p.  299). 

"In  the  third  chapter,  where  colour  characters  are  used  as  sub- 
jects, it  is  demonstrated  that  variation  is  directly  produced  by 
stimuli — that  from  relatively  invariable  parents,  stimuli  produce 
variable  offspring;  and  again  in  the  fifth  chapter  it  is  shown  that 
variations  arise  in  direct  response  to  stimuli"  (p.  300). 

"I  maintain,  therefore,  that  all  organic  variations  are  responsive 
to  stimuli,  and  are  not  due  to  inherent  tendencies  or  latencies,  or 
the  product  of  mystic  elements"  (p.  300). 

13  Montgomery,  T.  A.,  in  a  recent  book  of  much  interest  ("Anal- 
ysis of  Racial  Descent  in  Animals,"  1906),  explains  clearly  his  belief 
in  the  inevitable  production  of  variation  (even  that  called  blastogenic 
or  congenital),  and  the  influence  on  heredity   (through  this  varia- 
tion) by  the  influences  of  environment. 

14  Brooks,  W.  K.,  "The  Foundations  of  Zoology,"  p.  43,  1899.     A 
most  thoughtful  and  keen  discussion  of  many  of  the  conspicuous 
problems  of  "philosophical  biology,"  written  in  lucid  and  epigram- 
matic style.    In  many  ways  Brooks  stands  at  the  head  of  American 
philosophical  biologists. 


INDEX. 


Adaptation,  complex  and  cor- 
related, not  explicable  by 
selection,  144;  Friedlander's 
discussion  of,  392;  lack  of,  in 
egg-laying  habit  of  Phrygani- 
dia  calif ornica,  68;  the  great 
need  of  explaining,  380;  not 
all  explicable  by  Lamarckism, 
272 

Amphimixis,  Weismann's  prin- 
ciple of,  180 

Anosia,  mimicry  of,  by  Basi- 
larchia,  49 

Anti-Darwinism,    present-day,   4 

Baldwin,  J.  M.,  theory  of  ortho- 
plasy,  208 

Basilarchia,  mimicry  of  Anosia 
by,  49 

Bateson,  W.,  records  of  discon- 
tinuous variation,  33;  sugges- 
tion that  mutations  are  Men- 
delian  recessives,  351 

Battle  of  the  parts,  Roux's 
theory  of,  2OI 

Biologists,  many  not  satisfied 
with  the  selection  theory,  89 

Biophor,  195 

Brown-Sequard,  experiments  on 
guinea  pigs,  290 

Buffon,  theory  of  ultimate 
structure  of  protoplasm,  216 

Bumpus,  H.,  example  of  in- 
creased variability  due  to 
emancipation  from  selection, 
56 ;  references  to  papers  by,  69 

Burbank,  Luther,  belief  in  La- 
marckism, 272;  scientific  as- 
pects of  work  of,  310 

Callosamia    promethea,    Mayer's 
.    experiments  with,   120 
Carcinus,      Weldon's      selection 

experiments  on,   158 
Castle,     W.     S.,     discussion     of 

mutations  theory,  364 


Chance,  law  of,  variation  accord- 
ing to,  32-59 

Characters,  numerous,  useful 
only  in  highly  perfected  state, 
49;  species,  of  no  utility,  38 

Colour  and  pattern  of  insects, 
Piepers'  antagonism  to  selec- 
tion explanation  of,  69 

Conn,  H.  W.,  discussion  of  the 
chances  of  death,  83;  discus- 
sion of  selective  value,  182; 
statement  of  objection  to  se- 
lection, based  on  trivial  char- 
acters, 40 

Cope,  E.  D.,  belief  in  ortho- 
genetic  evolution,  323;  claim- 
ing that  natural  selection  can- 
not make  new  characters,  185; 
theory  of  orthogenesis,  285 

Correlation,  references  to  papers 
on,  184 

Crab,  hermit  and  polyp,  sym- 
biosis of,  23 

Crabs,  Weldon's  experiments  on, 
158. 

Cunningham,  J.  T.,  criticism  of 
Weldon's  experiments  on 
crabs,  161 ;  discussion  of 
orthogenesis,  326 ;  experiments 
on  flatfishes,  296;  explanation 
of  secondary  sexual  charac- 
ters, 354 ;  theory  to  explain  sec- 
ondary sexual  differences,  124 

Dall,  W.,  belief  in  sudden 
species-change,  330 

Darwin,  C.,  attitude  toward  de- 
terminate variation,  34 ;  basis 
of  theory  of  sexual  selection, 
112;  explanation  of  descent, 
13;  on  race  origin  from  sports, 
357 ;  theory  of  sexual  selec- 
tion, in;  theory  of  ultimate 
structure  of  protoplasm,  218 

Darwinism  attacked,  25 ;  attack 
on,  by  Dennert,  7;  concilia- 


397 


INDEX. 


tory  defence  of,  164 ;  death-bed 
of,  i ;  defended,  129 ;  defined, 
2,  10 ;  not  synonymous  with 
organic  evolution,  2,  3 ;  pres- 
ent standing  of,  374 ;  upheld 
by  Lankester,  389 

Davenport,  C.  B.,  discussion  of 
mutations  theory,  367 

Death-bed   of   Darwinism,    I 

Death  indiscriminate,  80 

Defence    of    Darwinism,    129 

Degeneration,  complete,  not  ex- 
plicable by  selection,  77,  146; 
example  of  progressive,  not 
explicable  by  natural  selection, 
100 ;  explanation  of,  by  pan- 
mixia, 190 ;  Lamarckian  ex- 
planation of,  192 ;  Plate's  La- 
marckian explanation  of,  147; 
'Tayler's  Darwinian  explana- 
tion of,  147 ;  Weismann's  dis- 
cussion of,  77 

Delage,  Y.,  criticism  of  Del- 
boeuf's  law,  72 ;  criticism  of 
organic  selection,  210;  esti- 
mate of  selection,  93,  390 ;  ma- 
chine theory  of  protoplasm, 
225;  theory  of  general  varia- 
tion, 289 

Delbceuf's  law,  Delage's  criti- 
cism of,  72 

Dennert,  E.,  attack  on  Darwin- 
ism, 7 

Descent,  Darwinian  explanation 
of,  13;  evidences  for,  17;  evi- 
dences of,  references,  23 ;  his- 
tory of  theory  of,  references, 
22;  natural  selection  the  final 
arbiter  in,  374;  relations  to 
theology,  references,  23;  theo- 
ries of,  187;  theory  of,  de- 
fined, ii ;  theory  of,  dis- 
tinguished from  theory  of  nat- 
ural selection,  17;  theory  of, 
history,  of,  n  ;  theory,  given 
validity  by  Darwin,  12;  theory, 
relation  to  pedagogy,  21 ; 
theory,  relation  to  sociology, 
21 ;  theory,  relation  to  theology 
and  philosophy,  20 

Determinant,  95 

DeVries,  H.,  belief  of,  that 
artificial  races  are  not  fixed 
and  constant  forms,  87 ;  dis- 
cussion of  geologic  time  and 


species-forming,  54;  discus- 
sion of  species-forming  by 
selection,  389;  objection  to 
selection  based  on  linear  char- 
acter of  variation,  139;  refer- 
ences to  discussions  of  muta- 
tions theory  by,  362 ;  summing 
up  of  discussion  of  compari- 
son of  natural  and  artificial 
selection,  89;  theory  of  muta- 
tions, 337;  theory  of  the  ulti- 
mate structure  of  protoplasm, 

220 

Dohrn,  A.,  principle  of  change 
of  function,  168 

Douglass,  N.  G.,  observations 
on  wall  lizard,  123 

Diirigen,  observations  on  liz- 
ards, 123 

Eimer,  Th.,  theory  of  ortho- 
genesis, 282,  321 

.Emery,  C.,  theory  of  primary 
variations,  332;  theory  of  the 
origin  of  secondary  sexual 
characters,  353;  theory  to  ex- 
plain secondary  sexual  differ- 
ences, 124 

Evolution,  defined,  10;  organic, 
not  synonymous  with  Darwin- 
ism, 2,  3;  Osborn's  champion- 
ship of  the  unknown  factors 
of,  391 ;  the  unknown  factors 
of.  377 

Evolution  study,  prime  needs  of, 
378 

Fischer,  experiments  with  but- 
terflies, 296 

Fleischmann,  A.,  opposed  to  evo- 
lution, 8 

Friedlander,  discussion  of  adap- 
tation, 392 

Friedman,  H.,  theory  of  the  con- 
vergence of  organisms,  8 

Galton,  F.,  belief  in  hetero- 
genesis,  332;  discussion  of 
specific  stability,  359;  discus- 
sion of  variation  according  to 
the  law  of  chance,  61  ;  law  of. 
regression,  71 ;  statement  of 
the  law  of  regression,  97 

Germ-cells,  theories  of  ultimate 
composition  of,  268 


INDEX. 


399* 


Grinnell,  Jos.,  study  of  geo- 
graphic differences  in  the 
chickadee,  225 

Gulick,  J.  T.,  studies  of  Ha- 
waiian land  snails,  251 ;  theo- 
ries of  isolation  influence,  249 

Haacke,  W.,  discussion  of  in- 
heritance of  acquired  char- 
acters, 270;  summary  of  Wag- 
ner's theory,  253 

Haeckel,  E.,  champion  of  evolu- 
tion, 130 

Hatschek,  B.,  theory  of  the 
ultimate  structure  of  proto- 
plasm, 222 

Henslow,  G.,  experiment  of  sow- 
ing of  wheat,  80 ;  references  to 
books  antagonistic  to  selection, 
67 

Heterogenesis,  326;  belief  in,  of 
Dall,  330;  Emery's  theory  of, 
332;  Korschinsky's  theory  of, 
333;  proposed  by  von  K61- 
liker,  330 

Hutton,  F.  W.,  argument  for 
dualism,  23 

Hyatt,  A.,  experiments  on 
Planorbis,  295 

Inheritance  of  acquired  char- 
acters. 263;  Brown-Sequard's 
experiments,  290 ;  Cunning- 
ham's experiments,  296;  diffi- 
culties in  accepting,  267;  ex- 
periments with  silkworms, 
Fischer's  experiments, 
Haacke's  discussion  of, 
270  Hyatt's  experiments,  295  ; 
logical  proof  of,  382;  Mont- 
gomery's explanation  of,  306 ; 
references  to  discussions  of, 
305 

Insects,  parthenogenetical  varia- 
tion in,  58 ;  variation  in,  62 

Interbreeding,  swamping  favour- 
able variations,  44 

Intra-selection,  Roux's  theory  of, 
201  ;  Plate's  criticism  of 
Roux's  theory  of,  203 

Isolation,  biologic,  243;  biologic, 
example  of,  243;  geographic, 
studied  among  past  animals, 
241;  defined,  234;  importance 
of,  in  species-forming,  232-; 


not  an  all-sufficient  agent  of 
species-forming,  242 ;  physio- 
logical, 245 ;  references  to  dis- 
cussions of,  253,  261 ;  sexual, 
245;  theories,  232;  various 
means  of  effecting,  234 

Jaeckel,    theory    of    metakinesis, 

289 
Johannsen,       W.,      experiments 

with  beans  bred  in  pure  lines, 

72 
Jordan,    Karl,   criticism   of  Ver- 

npn's    theory    of    reproductive 

divergence,  249 ;  on  mechanical 

selection,  246 
Jordan,    D.    S.,    on    geographic 

isolation,  237 

Kallima,  case  of,  explained  by 
Plate,  175 ;  over-specialisation 
of,  53 

Klebs,  G.,  experiments  on  plants, 
392 

Korschinsky,  H.,  radical  anti- 
selection  position  of,  91 ; 
theory  of  heterogenesis,  333 

Kramer,  P.,  classification  of  sec- 
ondary sexual  characters,  107 

Lamarck,  references  to  his  life 
and  writings,  290 

Lamarckism,  263;  Burbank's  be- 
lief in,  272;  favoured  by  Red- 
field,  305 ;  Plate's  discussion 
of,  273 ;  unable  to  explain  all 
adaptations,  272;  Weismann's 
attack  on,  266 

Lankester,  R.,  answer  to  objec- 
tion to  selection,  based  on  in- 
sufficient time,  55;  upholding 
of  Darwinism,  389 

Law,  Delboeuf's,  Delage's  criti- 
cisms of,  72;  of  chance,  varia- 
tion according  to,  32,  59;  of 
regression,  Galton's,  71 ;  of 
regression,  statement  of  Gal- 
ton,  97 

Le  Dantec,  F.,  chemical  theory 
of  protoplasm,  225 

Lizards,  experiments  on,  123 

Loeb,  J.,  attitude  toward  the 
problem  of  species-forming,. 
393 


INDEX. 


Mallophaga,  effects  of  isolation 
on,  240 

Mayer,  A.  G.,  experiments  on 
Promethca,  121  ;  experiments 
on  sexual  selection,  120 

Mendel,  G..  references  to  life  and 
work,  356 

Mendelism,  references  to  discus- 
sions of,  357 

Merriam,  C.  H.,  criticism  of 
mutations  theory,  367 

Metakinesis,  Jaeckel's  theory  of, 
289 

Mimicry  of  Anosia  by  Basi- 
larchia,  49 

Montgomery,  Th.,  explanation 
of  inheritance  of  acquired 
characters,  306 

Morgan,  C.  L.,  statement  of  con- 
ception of  organic  selection, 
230 ;-  theory  of  orthoplasy,  145, 
208;  answer  to  objections  to 
sexual  selection  theory,  149 

Morgan,  T.  H.,  antagonism  of 
species-forming  by  selection, 
93;  criticism  of  Weismann's 
method  of  argument,  229 ;  dis- 
cussion of  de  Vries's  theory, 
345 ;  objections  to  sexual  se- 
lection theory,  118;  summation 
of  the  advantages  of  the  muta- 
tions theory,  350 

Mutation,  as  used  by  Waagen, 
324;  de  Vries's  theory  of,  337 

Mutations  theory,  American 
opinion  of,  362;  attitude  of 
naturalists  toward,  348;  con- 
trasted with  Lamarckism,  349; 
contrasted  with  the  isolation 
factor,  349;  discussion  of,  by 
Castle,  364;  discussion  of,  by 
Davenport,  366,  367;  Mer- 
riam's  criticism  of,  367;  Mor- 
gan's-summation  of  the  ad- 
vantages of,  350;  Plate's 
criticism  of,  368;  references 
to  discussions  of,  by  de 
Vries,  362 


Nageli.  Ch.,  seven  objections  to 
species-forming  by  selection, 
62;  theory  of  orthogenesis, 
277 ;  theory  of  ultimate  struct- 
ure of  protoplasm,  219 


Neo-Darwinians,  concessions  of, 

134 
Neo-vitalism,  226 

Organisms,  number  of  living,  10 
Orthogenesis,  274;  Cope's  belief 

in,  323;  Cope's  theory  of,  285; 

Cunningham's    discussion    of, 

326;    Eimer's    theory    of,    282, 

320;    Nageli's   theory  of,   277; 

palaeontologists    in    favour    of, 

288;    Pfeffer's  theory  of,  320; 

Plate's  resume  of  evidence  for, 

279;  Whitman's  declaration  in 

favour  of,  288 
Orthoplasy,    208;    references    to 

discussions  of,  229 
Orthoselection,    contrasted    with 

orthogenesis,  276 
Osborn,  H.  F.,  championship  of 

the  unknown  factors,  of,  391 ; 

theory  of  orthoplasy,  208 

Palaeontologists  favouring  ortho- 
genesis, 288 

Panmixia,  example  of  ineffect- 
ive, M)\  Weismann's  theory  of, 
i88;Wolff's  criticism  of,  98 

Parallelism  in  variation,  279 

Parthenogenesis,  variation  in  in- 
sects produced  by,  58 

Pearson,  K.,  discussion  of  varia- 
tion according  to  the  law  of 
chance,  61 ;  theory  of  repro- 
ductive selection,  249 

Pedagogy,  relation  of,  to  theory 
of  descent,  21 

Pfeffer,  G.,  objection  to  selec- 
tion, based  on  the  smallness  of 
species-change,  75 ;  statement 
of  the  fundamental  difference 
between  natural  and  artificial 
selection,  88;  theory  of  ortho- 
genesis, 320 

Philosophy,  relation  to  biology, 
references  for,  24;  relation  to 
theory  of  descent,  20 

Phryganidia  californica,  lack  of 
adaptation  in  egg-laying  habit, 
68 

Piepers,  M.  C.,  antagonism  to 
selection  explanations  of 
colour  and  pattern  in  insects, 
69 


INDEX. 


401 


Plant-breeding,    references    for, 

105 

Plants,  amelioration  of,  refer- 
ences for,  105 

Plate,  L.,  admission  of  the  need 
of  acquired  characters  to  aid 
selection,  170,  178;  answer  to 
the  claimed  improbability  of 
timely  appearance  of  varia- 
tions needed  in  co-adaptive 
structures,  176;  answer  to  the 
objection  concerning  the  de- 
pendence of  selection  on 
chance,  170;  answer  to  the  ob- 
jection to  selection  based  on  the 
slightness  of  Darwinian  varia- 
tions, 165;  claim  that  correla- 
tion may  aid  slight  variation, 
167;  claim  that  same  selective 
value  may  be  obtained  in  dif- 
fe"rent  ways,  172;  claim  that 
selection  works  with  plural 
variation,  172;  classification  of 
secondary  sexual  characters 
by,  107;  conciliatory  defence 
of  Darwinism,  164;  criticism 
of  mutations  theory,  368; 
criticism  of  organic  selection, 
210;  criticism  of  Roux's 
theory  of  intra-selection,  203; 
discussion  of  Lamarckism, 
273;  disbelief  in  Weismann's 
principle  of  germinal  selection, 
180 ;  explanation  of  character 
fixity  in  domestic  animals,  163 ; 
explanation  of  the  case  of 
Kallima,  175 ;  Lamarckian  ex- 
planation of  degeneration, 
147 ;  recognition  of  the  weight 
of  certain  objections  to  Dar- 
winism, 181 ;  resume  of  facts 
tending  to  prove  orthogene- 
sis, 279 ;  reviewer  of  criticisms 
of  Darwinism,  30 

Podocoryne  and  hermit  crab, 
symbiosis  of,  23 

Polyp  and  hermit  crab,  symbiosis 
of  23 

Promethea,  Mayer's  experiments 
on,  121 

Protoplasm,  micromeric  theo- 
ries of  structure  of,  215; 
physical  and  chemical  struct- 
ure of,  194;  theories  of  ulti- 
mate structure  of,  214;  Weis- 


mann's theory  of  the  ultimate 
structure  of,  195 

Quetelet,  discoverer  of  variation 
according  to  the  law  of  chance, 
61 

Redfield,  C,  favouring  Lamarck- 
ism,  305 

Regression,  Galton's  law  of,  71 ; 
statement  of  Galton's  law  of, 
07 

Romanes,  G.  J.,  discussion  of 
Gulick's  work  and  conclusions, 
250 ;  on  physiological  selection, 

245 

Rosa,  D.,  theory  of  progressive 
reduction  of  variability,  322 

Roux,  W.,  theory  of  intra- 
selection  or  battle  of  the  parts, 

201 

Secondary  sexual  characters, 
Cunningham's  explanation  of, 
354;  Emery's  theory  of  the 
origin  of,  353 ;  references  to 
exposition  of  theories,  373 ; 
Wallace's  suggested  explana- 
tion of,  354 

Seebohm's  criticism  of  physio- 
logic selection,  247 

Selection,  artificial,  defined,  15; 
artificial,  natural  selection 
resting  too  largely  on  an  anal- 
ogy with,  86 ;  based  on  varia- 
tion, 30;  cannot  explain  com- 
plete degeneration,  77 ;  co- 
efficient, Wolff's  discussion  of, 
101 ;  Darwin's  theory  of  sex- 
ual, in;  Delage's  estimate  of, 
390;  de  Vries's  discussion  of 
species-forming  by,  389;  de 
Vries's  estimate  of, ,  93  ;  diffi- 
culty of  explainin^-^complex 
relations  among  body-parts  by, 
51 ;  difficulty  of  explaining 
inter-species  sterility  by,  76; 
difficulty  of  explaining  repeated 
identical  structures  by,  47 ;  ex- 
ample of  persistence  of  trivial 
differences  in  face  of,  103; 
example  of  progressive  degen- 
eration, not  expjicable  by,  100; 
final  arbiter  in  descent*  374; 
geologic  time  too  short  to 


402 


INDEX. 


give  it  opportunity  to  do  its 
work,  54;  hindering  rather 
than  promoting  species  change, 
56 ;  Korschinsky's  radical  posi- 
tion against,  91 ;  may  produce 
continuous  change,  but  not  dis- 
continuous series  of  species, 
73 ;  Morgan's  antagonism  of 
species-forming  by,  93;  natu- 
ral, defined,  13;  natural,  needs 
sexual  selection  theory  for 
support,  125;  natural,  rests  too 
largely  on  analogy  with  arti- 
ficial selection,  150;  needs  the 
support  of  the  sexual  selection 
theory,  85 ;  not  able  to  explain 
complex  adaptation,  144 ;  not 
able  to  explain  degeneration, 
146 ;  not  able  to  explain  over- 
specialisation,  146;  not  able 
to  produce  many-branched  de- 
scent and  discontinuity  in 
series,  142;  objection  to,  based 
on  the  linear  and  quantitative 
character  of  fluctuating  varia- 
tions, 70;  objections  to  based 
on  over-specialisation,  53 ;  per- 
sonal, how  real,  82 ;  Pfeffer's 
objection,  based  on  the  small- 
ness  of  species  change,  75 ; 
rests  too  largely  on  an  analogy 
with  artificial  selection,  86 ; 
rigour  of,  questioned,  148 ; 
theories,  Wigand's  criticism 
of,  387;  theory  of,  dis- 
tinguished from  theory  of  de- 
scent, 17 

Selection,  germinal,  objection  to 
theory  of,  200 ;  germinal,  Weis- 
mann's  theory  of,  188,  193 ; 
germinal,  resulting  in  deter- 
minate variation,  198 

Selection,  mechanical,  246 

Selection,   ontogenetic,   208 

Selection,  organic,  208;  organic, 
Delage  and  Plate's  criticisms 
of,  210 

Selection,  physiological,  criti- 
cisms of,  247 

Selection,  reproductive,  Pear- 
son's theory  of,  249 

Selection,  sexual,  106,  120;  al- 
ternative explanations  of,  124; 
answers  to  objections  to,  148; 
criticism  of,  by  Wolff,  G.,  126; 


criticism  of  theory  of,  113; 
Darwin's  basis  of  theory,  112; 
defined,  16;  Morgan's  objec- 
tions to,  118;  other  theories  to 
replace  theory  of,  123;  refer- 
ences to  discussions  of,  125 

Selectionists,   concessions   of,   90 

Sexual  differences,  classification 
of  secondary,  107;  secondary, 
106;  significance  of,  no 

Snodgrass,  R.  E.,  studies  on  bills 
of  Galapagos  birds,  323; 
studies  on  biologic  selection, 
245 

Sociology,  relations  to  biology, 
references  for,  24;  relation  to 
theory  of  descent,  21 

Species-forming,  causes  and 
means  of  segregation  the  chief 
factors  in,  377;  determinate 
variation  as  a  factor,  33;  de 
Vries's  discussion  of,  by  selec- 
tion, 389;  Loeb's  attitude  to- 
ward the  problem  of,  393  ;  on 
a  basis  of  fluctuating  varia- 
tion, 35 ;  theories  of,  187  ; 
Tower's  experiments  and  con- 
clusions, 309,  394 

Spencer,  H.,  example  of  the 
femur  of  the  whale,  38;  pic- 
ture of  the  inutility  of  ad- 
vantage in  a  single  direction, 
48 ;  theory  of  ultimate  struct- 
ure of  protoplasm,  216 

Sport  in  cattle,  recent  example 
of,  358 

Sterility,  inter-species,  difficulty 
of  explaining  by  selection,  76 

Struggle  for  existence,  actual 
rigour  of,  79;  defined,  13 

Symbiosis  of  hermit  crab  and 
polyp,  23 


Tayler,  J.  L.,  answer  to  objec- 
tion to  selection  based  on 
linear  variation,  141 ;  Darwin- 
ian explanation  of  degenera- 
tion, 147;  explanation  of  de- 
generation by  natural  selec- 
tion, 162;  general  defence  of 
natural  selection,  153 

Theology,  relation  of,  to  theory 
of  descent,  20 

Tower,  W.  L.,  experiments  and 


INDEX. 


403 


conclusions    on    species-form- 
ing, 309,  394 

Ultra-Darwinism,        reaction 

against,   130 
Utility,  many  species  characters 

of   no,    38 

Variation  according  to  the  law 
of  chance,  32,  59;  causes  of,  and 
means  of  segregation  the  chief 
factors  in  species-forming, 
377 ;  determinate,  apparent 
cases  of,  319;  determinate,  as 
a  species-forming  factor,  33 ; 
determinate,  produced  by 
germinal  selection,  198;  de- 
terminate, Whitman's  belief 
in,  325;  discontinuous,  33, 
328;  favourable,  swamped  by 
inter-breeding,  44;  fluctuating, 
as  a  basis  for  species-forming, 
35 ;  fluctuating,  insignificance 
of,  36;  fluctuating,  of  linear 
and  quantitative  value  only, 
139;  fluctuating,  too  slight  to 
be  of  selective  value,  138;  gen- 
eral, Delage's  theory  of,  289; 
how  cumulated,  379;  in  in- 
sects, 62;  in  parthenogenetic 
insects,  58 ;  natural  selection 
based  on,  30;  necessity  for  co- 
incident appearance  of  other, 
to  make  a  certain  one  effect- 
ive, 46 ;  non-correlated  in  bi- 
laterally repeated  organs,  65 ; 
occurrence  of  needed  coin- 
cident, 45 ;  orthogenetic,  in 
palaeontology,  319;  parallelism 
in,  279;  references  for,  57; 
suggestion  concerning  the 
cause  of,  384 

Vejodoysky,  example  of  pro- 
gressive degeneration  not  ex- 
plicable by  natural  selection, 
100 

Vernon,  H.  M.,  theory  of  repro- 
ductive divergence,  248;  theory 
of  the  ultimate  structure  of 
protoplasm,  225 

Vestigial  structures,  explanation 


of,     by    panmixia,     190;     La- 
marckian   explanation    of,    192 
Von  Kolliker,  R.,  proposal  of  a 
theory  of  heterogenesis,  330 

Waagen,  use  of  term  mutation, 

324 

Wagner,  M.,  formulation  of 
Separations  -theorie,  236 ; 
founder  of  theory  of  species- 
forming  by  geographic  isola- 
tion, 234 

Wallace,  A.  R.,  criticism  of  Ro- 
manes's theory,  247 ;  suggested 
explanation  of  secondary 
sexual  characters,  354 

Weismann,  A.,  admission  of  ob- 
jections to  selection,  45;  at- 
tack on  Lamarckism,  266;  dis- 
cussion of  degeneration,  77 ; 
principle  of  amphimixis,  180; 
references  to  evolution  writ- 
ings of,  212;  theory  of  germi- 
nal selection,  188,  193;  theories 
of  neo-Darwinism  and  neo- 
Lamarckism,  133 ;  theory  of 
panmixia,  188 

Weldon,  selection  experiments 
on  Carcinus,  158 

Whitman,  C.  O.,  belief  in  deter- 
minate variation,  325;  favour- 
ing orthogenesis,  288 

Wolff,  G.,  attack  on  the  assump- 
tion by  selectionists  of  the  ap- 
pearance at  the  right  time  of 
the  needed  variation,  64; 
criticism  of  panmixia  by,  98 ; 
criticism  of  sexual  selection, 
126 ;  discussion  of  selection,  co- 
efficient, 101 ;  objections  to  ex- 
planation by  selection  of  com- 
plex related  body-parts,  51 ; 
objection  to  natural  selection, 
based  upon  its  dependence  on 
sexual  selection  theory,  125 ; 
objections  to  sexual  selection 
theory,  126;  objection  that 
selection  can  concern  only 
quantitative  changes,  70;  ob- 
jection to  the  assumption  by 
selectionists  of  identical  and 
coincident  variation,  67 


AMERICAN  INSECTS 

BY  VERNON  L.  KELLOGG 

PROFESSOR    IN    LELAND    STANFORD,   JR.,    UNIVERSITY 

WITH  812  figures  and  n  colored  plates;  647  pp. 
(American  Nature  Series,  Group  /);  $5.00  net 
(postage  34  cents).  Students'  edition,  $4.00.  A 
comprehensive  account  of  the  natural  history  of  the  in- 
sects of  America,  written  simply  yet  seriously,  so  as  to 
be  acceptable  to  the  general  reading  public  as  well  as  to 
professional  students  of  nature.  All  of  the  insect  orders 
represented  in  our  country  are  treated  in  this  single 
volume,  which,  despite  its  comprehensiveness  and  its 
profusion  of  illustrations,  is  so  compactly  made  as  to  be 
in  no  way  unwieldy.  The  book  may  be  used  for  con- 
tinuous reading  by  those  wishing  to  inform  themselves 
concerning  the  kinds  and  habits  of  American  insects  in 
general,  or  as  a  reference  manual  for  authoritative  in- 
formation on  classification,  specific  remedies  for  certain 
pests,  special  discussions  of  structural,  physiological,  or 
ecological  phases  of  insect  biology,  etc. 

I        "Certain  to  be  widely  useful  .  .  .  readable  and  profusely  illus- 

trated.   It  gives  a  great  amount  of  information  about  the  insects 

of  this  country,  in  such  a  manner  that  it  is  available  to  any  intel- 

'     ligent  person  .  .  .  other  works  are  necessary  for  particular  pur- 

'     poses  ;  but  if  I  were  asked  to  name  a  single  work  for  a  beginner, 

'     who  at  the  same  time  meant  business,  1  should  not  hesitate   to 

i     recommend  this  new  product  of  Stanford  University."— 7'.  D.  A. 

\     Cocker  ell  in  The  Dial. 

"  Nothing  needed  to  make  this  a  complete  guide  to  the  study  of 
our  American  insects  has  been  omitted." — M.  A.  Bigelow  in  the 
Independent. 

"Professor  Kellogg's  volume  will  be  welcomed  as  one  of  the 
best  general  text-books  on  the  subject  covered."— C.  L.  Marlatt 
in  Science. 

"The  work  is  scientifically  conceived  and  carefully  executed 
in  every  part ;  but  it  is  free  from  all  unnecessary  technicalities 
and  so  fresh  in  its  spirit  and  so  informal  in  its  tone  that  one 
scarcely  remembers  in  reading  it  the  scientific  attainments  of  its 
eminent  author.  It  is  a  storehouse  of  biological  information 
drawn  from  authoritative  sources  and  vivified  by  contributions 
from  the  author's  own  rich  experience  as  an  observer  and  an  in- 
vestigator. .  .  .  The  style  is  vivacious,  flowing,  correct,  as  pel- 
lucid as  a  mountain  brook,  and  free  from  all  those  affectations  of 
sprightliness  or  sentiment  which  seem  likely  to  become  conven- 
tional in  the  literature  of  nature  study."— S.  A.  Forbes  in  School 
Science. 

"  An  excellent  work,  and  we  can  heartily  recommend  it  to  all 
who  are  interested  in  the  classification  and  natural  history  of  in- 
sects. It  is  written  in  an  agreeable  and  attractive  style  and  can 
be  referred  to  anywhere  by  the  ordinary  reader  without  fear  of 
being  disheartened  by  purely  technical  language  .  .  .  the  greater 


part  of  the  large  volume  is  clear  and  simple  and  most  interesting 
to  every  Nature  Student.  .  .  .  No  one  can  take  up  the  book  and 
open  it  any  where  without  becoming  deeply  interested  in  the  sub- 
ject treated  of,  whatever  it  may  be,  provided,  that  is,  that  he  has 
any  love  at  all  for  living  creatures,  any  interest  in  the  myriad 
forms  and  modes  of  life  of  these  wonderful  beings  that  are 
everywhere  about  us." — Canadian  Entomologist. 

"  Sumptuous,  delicate,  exquisite,  these  are  the  words  that  easily 
leap  to  our  lips  in  looking  through  the  book.  But  I  cannot  too 
much  emphasize  the  fact  that  in  the  volume  we  also  have  science 
made  thoroughly  readable."— .#.  P.  Powell  in  Unity. 

"Is  probably  the  most  valuable  handbook  of  the  subject  for 
the  technical  student  or  amateur  collector." — Kansas  Farmer. 

"Ein  ebenso  reichhaltiges  wie  luxuries  ausgestattetes  Werk 
zur  Einfiihrung  in  das  Studium  der  Biologic  der  amerikanischen 
Insekten." — Edm.  Reitter  in  Wiener  Ent.  Zeitung. 

"The  book  is  of  the  first  importance  in  its  class." — Out  West. 

"This  work  easily  ranks  as  the  most  comprehensive  volume 
treating  of  American  insects  yet  produced.  .  .  .  The  subject- 
matter  is  presented  in  an  easy  narrative  style,  though  accuracy 
is  not  sacrificed  for  the  sake  of  popularity.  .  .  .  The  volume  ex- 
hibits a  thorough  appreciation  of  and  familiarity  with  recent  in- 
vestigations. .  .  .  This  work  brings  together  in  one  volume  a 
vast  amount  of  information  and  the  author  is  to  be  congratulated 
upon  having  produced  a  very  readable,  comprehensive  work, 
which  should  prove  attractive  and  exceedingly  helpful  to  the 
amateur  as  well  as  essential  to  every  investigator."—^.  P.  Pelt 
in  Psyche. 

"  We  have  in  this  single  volume  a  whole  library  of  insect  lore." 
—N.  Y.  Critic. 

"  Es  ist  ein  gewaltiges  Unternehmen,  das  Verf.  in  diesem 
Werke  zur  Durchfiihrung  gebracht  hat  und  die  vollendete  Art 
und  Weise  dieser  Durchfiihrung  diirfte  dem  Buche  in  seinem 
Vaterlande  einen  vollen  Erfolg  sichern.  Es  will  seinen  Lesern 
eine  Uebersicht  iiber  die gesamrnte Insektenwelt geben,aber  nicht 
in  dem  oberflachlichen  Feuilletonstil,  den  man  in  derartigen 
Werken  haufig  rindet,  sondern  mit  wirklichen  wissenschaft- 
licher  Grtindlichkeit,  und  das  ist  dem  Verfasser  vorziiglich 
gelungen." — Zeitschr.Jilr  wissenschaftliche  Jnsektenbiologie. 

"  The  work  is  probably  the  best  that  exists  for  anyone  desiring 
an  introductory  work  on  North  American  insects  compressed 
into  a  single  volume."— David  Sharp  in  Nature. 

"  We  are  glad  to  see  the  interesting  chapter  on  insects  and  dis- 
ease, as  it  places  the  subject  on  a  higher  plane  with  the  general 
?ublic,  and  is  a  matter  of  immense  importance  to  humanity, 
'aking  the  work  in  its  entirety  it  is  a  valuable  contribution  to 
the  subject,  and  can't  fail  to  be  useful  to  the  student  beginner 
as  well  as  to  entomologists  in  general."— Entomological  l\ews. 

"To  many  readers,  especially  to  those  who,  whilst  studying 
specially  one  order,  want  a  clear  explanation  of  the  general 
character  and  biology  of  the  other  orders,  the  book  must  be  a 
precious  boon,  from  which  the  fact  that  the  illustrations  are 
taken  from  American  insects  detracts  nothing.  Dr.  Kellogg  has 
long  undoubtedly  been  in  the  first  rank  of  American  entomolo- 
gists, and  this  latest  work  can  only  add  lustre  to  an  already 
distinguished  name."—/.  W.  Tutt  in  Entomologist's  Record 
(London). 

HENRY   HOLT    AND   COMPANY 

PUBLISHERS  NEW  YORK 


1  DA.  USE 


H 


YC   1509! 


